Webbing take-up device

ABSTRACT

To obtain a webbing take-up device that can not only transmit to a take-up shaft only rotation from a motor by a clutch but is also simple and compact. 
     A clutch of this webbing take-up device has a simply configuration where sliders  144  of a clutch body portion  114  are caused by frictional force to be retained in a case, whereby the sliders  144  and lock bars  154  are caused to relatively move and the lock bars  154  are caused by this relative movement to move to positions where they engage with or disengage from a ratchet  134 . Consequently, the overall configuration of a clutch  100  can be made significantly compact (thinned) in comparison to a configuration that causes a pawl to move using an inertial disk that is large and has weight as in a conventional clutch. Thus, the overall configuration of a webbing take-up device  10  can be made compact.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of commonly owned, co-pending U.S.patent application Ser. No. 10/594,748, filed Feb. 12, 2008.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a webbing take-up device, and inparticular to a webbing take-up device that can take up a webbing by amotor causing a take-up shaft to rotate.

2. Background Art

Seat belt devices for restraining passengers are disposed with a webbingtake-up device. Among these webbing take-up devices, there is a webbingtake-up device disposed with a tension reducer mechanism for alleviatingor eliminating an excessive feeling of tightness when the webbing isworn and a pretensioner mechanism that eliminates slight looseness knownas “slack” or the like by causing a certain amount of the webbing to betaken up on a take-up shaft when the vehicle suddenly decelerates or thelike to increase the restraining force on the body of the passenger bythe webbing and more reliably hold the body of the passenger. Moreover,a motor retractor of a configuration where these functions are performedby a motor is known (see Patent Document 1 and Patent Document 2 forexamples).

This type of motor retractor can not only perform the functions of atension reducer and a pretensioner as described above, for example, butcan also assist in the taking up and pulling out of the webbing duringordinary wearing of the webbing, which is extremely beneficial.

Further, here, and particularly in recent years, a motor retractor isbeing considered which has a configuration where the distance to anothervehicle or an obstacle which is ahead is detected by a forwardmonitoring device such as a distance sensor, the motor is actuated whenthe distance to the other vehicle or obstacle which is ahead becomesless than a certain value, and the take-up shaft is caused to rotate ina take-up direction by the rotational force of the motor. This kind ofmotor retractor is configured such that a clutch is intervened betweenan output shaft of the motor and the take-up shaft so that the clutchtransmits to the take-up shaft only the rotation from the motor outputshaft in order to prevent rotation from the take-up shaft from beingtransmitted to the motor.

Incidentally, this kind of conventional motor retractor is disposed, forexample, with an inertial disk and a spring that biases the inertialdisk in a predetermined direction, and the motor retractor is configuredto utilize inertial force acting on the inertial disk to cause a pawl tomove and couple to and disengage from the clutch. For this reason, therehas been the problem that it is necessary to ensure the size and weightof the inertial disk, which leads to the clutch becoming larger overall.

-   Patent Document 1: JP-A No. 2001-130376-   Patent Document 2: JP-A No. 2001-347923

DISCLOSURE OF THE INVENTION Problem that the Invention is to Solve

In view of the aforementioned circumstances, it is an object of thepresent invention to obtain a webbing take-up device that can not onlytransmit just the rotation of the motor to the take-up shaft by a clutchbut is simple and compact.

Means for Solving the Problem

A first aspect of the invention is a webbing take-up device comprising:a take-up shaft around which a webbing for restraining a passenger iswound such that the webbing can be taken up and pulled out; a motor; anda clutch that is mechanically intervened between the motor and thetake-up shaft, transmits the rotation of the motor to the take-up shaftto cause the take-up shaft to rotate, and cuts off the transmission ofrotation arising at the take-up shaft side to prevent that rotation frombeing transmitted to the motor, wherein the clutch includes a rotatingbody that is disposed coaxially with respect to the take-up shaft androtates as a result of the rotation of the motor being transmitted tothe rotating body, sliders that are configured to be relatively movablewithin a predetermined range with respect to the rotating body, and lockbars that are disposed on the rotating body and ordinarily retained bythe sliders in positions where the lock bars are disengaged from thetake-up shaft, and when the rotating body rotates in one direction aboutits axial line, the lock bars engage with the take-up shaft, transmit tothe take-up shaft the rotation of the rotating body in the one directionabout its axial line, and allow the relative rotation of the take-upshaft with respect to the rotating body in the one direction about itsaxial line, and when the rotating body rotates in the other directionabout its axial line, the lock bars are moved to and retained in thedisengaged positions by the sliders.

The webbing take-up device based on this aspect is disposed with theclutch that transmits the rotation of the motor to the take-up shaft.The clutch includes the rotating body, which rotates as a result of therotation of the motor being transmitted to the rotating body, and thelock bars, which are disposed on the rotating body and engage with thetake-up shaft to transmit to the take-up shaft the rotation of therotating body in the one direction about its axial line. The lock barsare ordinarily retained by the sliders in positions where the lock barsare disengaged from the take-up shaft. For this reason, the rotatingbody and the take-up shaft are ordinarily mutually relatively rotatable,and rotation arising at the take-up shaft side is prevented from beingtransmitted to the motor.

Thus, when a passenger seated in the seat of the vehicle pulls thewebbing stored in the webbing take-up device, the webbing is pulled outwhile the take-up shaft rotates. Thus, when the passenger places thepulled-out webbing around his/her body and, for example, causes a tongueplate disposed on the webbing to engage with a buckle device, thepassenger can wear the webbing on his/her body.

Moreover, when the motor rotates, the rotating body of the clutch isrotated in one direction about its axial line. At this time, therotating body relatively moves within a predetermined range with respectto the sliders, the retention of the lock bars by the sliders isreleased, and the lock bars disposed on the rotating body engage withthe take-up shaft. Thus, the rotation of the rotating body in the onedirection about its axial line is transmitted to the take-up shaft viathe lock bars, and the take-up shaft is rotated in the one directionabout the axial line.

Moreover, in this state, because the lock bars allow the relativerotation of the take-up shaft with respect to the rotating body in theone direction about its axial line, it is also possible to cause thetake-up shaft to be forcibly rotated, by a separate pretensioner deviceor the like, in the one direction about the axial line independent ofthe motor.

On the other hand, when the motor reversely rotates, the rotating bodyof the clutch is rotated in the other direction about the axial line. Atthis time, the rotating body relatively moves within a predeterminedrange with respect to the sliders, and the lock bars disposed on therotating body are again moved to and retained in the positions where thelock bars are disengaged from the take-up shaft by the sliders. Thus,the rotating body and the take-up shaft again become relativelyrotatable, and free rotation of the take-up shaft becomes possible.

Here, the clutch of this webbing take-up device has a simpleconfiguration where, as described above, the sliders and the lock barsare caused to relatively move such that the lock bars are caused by thisrelative movement to move to the positions where the lock bars engagewith or disengage from the take-up shaft. Consequently, the overallconfiguration of the clutch can be made significantly compact incomparison to a configuration where a pawl is moved using an inertialdisk that is large and has a certain weight as in a conventional clutch.Thus, the overall configuration of the webbing take-up device can bemade compact.

A second aspect of the invention is a webbing take-up device comprising:a take-up shaft around which a webbing for restraining a passenger iswound such that the webbing can be taken up and pulled out; a motor; anda clutch that is mechanically intervened between the motor and thetake-up shaft, transmits the rotation of the motor to the take-up shaftto cause the take-up shaft to rotate in the webbing take-up direction,and cuts off the transmission of rotation arising at the take-up shaftside to prevent that rotation from being transmitted to the motor,wherein the clutch includes a case, a rotating body that is disposedcoaxially with respect to the take-up shaft and rotates as a result ofthe rotation of the motor being transmitted to the rotating body, aratchet that is integrally coupled to the take-up shaft, sliders thatare configured to be relatively movable within a predetermined rangewith respect to the rotating body as a result of being retained in thecase by frictional force, and lock bars that are disposed on therotating body, are always biased in a direction in which the lock barsengage with the ratchet, and are ordinarily retained by the sliders inpositions where the lock bars are disengaged from the ratchet, and whenthe rotating body rotates in the webbing take-up direction, the lockbars move away from the sliders such that the retention is released,engage with the ratchet by the biasing force, transmit to the ratchetthe rotation of the rotating body in the webbing take-up direction, andallow the relative rotation of the ratchet with respect to the rotatingbody in the webbing take-up direction, and when the rotating bodyrotates in the webbing pullout direction, the lock bars move toward thesliders and are moved to and retained in the disengaged positions by thesliders.

The webbing take-up device based on this aspect is disposed with theclutch that transmits the rotation of the motor to the take-up shaft.The clutch includes the rotating body that rotates as a result of therotation of the motor being transmitted to the rotating body, theratchet that is integrally coupled to the take-up shaft, and the lockbars that are disposed on the rotating body and engage with the ratchetto transmit to the ratchet the rotation of the rotating body in thewebbing take-up direction. The lock bars are always biased in thedirection in which they engage with the ratchet and are ordinarilyretained by the sliders in the positions where the lock bars aredisengaged from the ratchet. For this reason, the rotating body and theratchet are ordinarily mutually relatively rotatable, and rotationarising at the take-up shaft side is prevented from being transmitted tothe motor.

Thus, when a passenger seated in the seat of the vehicle pulls thewebbing stored in the webbing take-up device, the webbing is pulled outwhile the take-up shaft rotates in the webbing pullout direction. Thus,when the passenger places the pulled-out webbing around his/her bodyand, for example, causes a tongue plate disposed on the webbing toengage with a buckle device, the passenger can wear the webbing onhis/her body.

Moreover, when an obstacle is present in front of the vehicle while thevehicle is traveling and the distance between the vehicle and theobstacle (the distance from the vehicle to the obstacle) comes within apredetermined range, the motor rotates and the rotating body of theclutch is rotated in the webbing take-up direction. At this time,because the sliders are retained in the case by frictional force, therotating body relatively moves within a predetermined range with respectto the sliders, and the lock bars disposed on the rotating body moveaway from the sliders.

For this reason, the lock bars engage with the ratchet by frictionalforce, and the rotation of the rotating body in the webbing take-updirection is transmitted to the ratchet via the lock bars. Thus, theratchet is rotated in the webbing take-up direction, and the take-upshaft integrally coupled to the ratchet is rotated in the webbingtake-up direction. Thus, the webbing is taken up on the take-up shaft,slight looseness called “slack” of the webbing in the worn state iseliminated, and the restraining force on the body of the passenger bythe webbing can be raised.

Moreover, in this state, because the lock bars allow the relativerotation of the ratchet (the take-up shaft) with respect to the rotatingbody in the webbing take-up direction, it is also possible to cause thetake-up shaft to be forcibly rotated in the webbing take-up direction bya separate pretensioner device or the like when, for example, acollision of the vehicle can no longer be avoided in a state where the“slack” has been eliminated as described above. In this case, therestraining force on the body of the passenger by the webbing can beraised even more, and injury to the passenger in the event of a vehiclecollision can be kept to a minimum.

On the other hand, when the danger of a vehicle collision has beenavoided as described above, the motor is reversely rotated and therotating body of the clutch is rotated in the webbing pullout direction.At this time, because the sliders are retained in the case by frictionalforce, the rotating body relatively rotates with respect to the slideswithin a predetermined range, and the lock bars disposed on the rotatingbody move toward the sliders. For this reason, the lock bars are againmoved to and retained in the positions where they are disengaged fromthe ratchet by the sliders. Thus, the rotating body and the ratchetagain become relatively rotatable, and free rotation of the take-upshaft becomes possible.

Here, the clutch of this webbing take-up device has a simpleconfiguration where, as described above, the sliders are caused to beretained in the case by frictional force, whereby the sliders and thelock bars are caused to relatively move such that the lock bars arecaused by this relative movement to move to the positions where the lockbars engage with or disengage from the ratchet. Consequently, theoverall configuration of the clutch can be made significantly compact incomparison to a configuration where a pawl is moved using an inertialdisk that is large and has a certain weight as in a conventional clutch.Thus, the overall configuration of the webbing take-up device can bemade compact.

In a third aspect of the invention, the rotating body of the webbingtake-up device based on the first or second aspect includes: a gearwheel that rotates as a result of the rotation of the motor beingtransmitted to the gear wheel; a rotor that supports the lock bars; andspring pawls that are disposed between the gear wheel and the rotor,couple both to each other, and transmit the rotation of the gear wheelto the rotor, and when a load equal to or greater than a predeterminedvalue acts on the rotor, the spring pawls cut off the transmission ofrotation between the gear wheel and the rotor by the load to enable bothto relatively idle.

In the webbing take-up device based on this aspect, when the gear wheelis rotated by the rotation of the motor, this rotation is transmitted tothe rotor via the spring pawls and the rotor is rotated. For thisreason, because the lock bars supported on the rotor relatively movewithin a predetermined range with respect to the sliders, retention ofthe lock bars by the sliders and release of this retention can beperformed by switching the rotational direction of the motor.

When, for example, a load equal to or greater than a predetermined valueacts on the take-up shaft from the webbing in a state where the take-upshaft and the rotor are coupled together by the lock bars, a load equalto or greater than a predetermined value acts on the rotor via the lockbars. When a load equal to or greater than a predetermined value acts onthe rotor, the spring pawls cut off the transmission of the rotationbetween the gear wheel and the rotor by this load and enable both torelatively idle (load limiter mechanism). Thus, the take-up shaftcoupled to the rotor via the lock bars can be prevented from beingrotated with a force more than necessary by the driving force of themotor.

A fourth aspect of the invention is a webbing take-up device comprising:a take-up shaft around which a webbing for restraining a passenger iswound such that the webbing can be taken up and pulled out; a motor; anda clutch that is mechanically intervened between the motor and thetake-up shaft, transmits the rotation of the motor to the take-up shaftto cause the take-up shaft to rotate, and cuts off the transmission ofrotation arising at the take-up shaft side to prevent that rotation frombeing transmitted to the motor, wherein the clutch includes a rotatingbody that is disposed coaxially with respect to the take-up shaft androtates as a result of the rotation of the motor being transmitted tothe rotating body, sliders that are configured to be relatively movablewithin a predetermined range with respect to the rotating body andinclude push retention pieces that protrude toward one side in themoving direction, and lock bars that are disposed on the rotating body,are always biased in a direction in which they engage with the take-upshaft, include release pieces that protrude toward the push retentionpieces of the sliders, and are ordinarily retained in positions wherethe lock bars are disengaged from the take-up shaft as a result of therelease pieces engaging with the push retention pieces, and when therotating body rotates in one direction about its axial line, the lockbars move away from the sliders such that the retention is released,engage with the take-up shaft by the biasing force, and transmit to thetake-up shaft the rotation of the rotating body in the one directionabout its axial line, and when the rotating body rotates in the otherdirection about its axial line, the lock bars move toward the slidersand are moved to and retained in the disengaged positions as a result ofthe release pieces engaging with the push retention pieces, and at leastone of the push retention pieces of the sliders and the release piecesof the lock bars include retention portions that cause predetermineddrag to arise with respect to the movement of the sliders away from thelock bars when the rotating body is stopped.

The webbing take-up device based on this aspect is disposed with theclutch that transmits the rotation of the motor to the take-up shaft.The clutch includes the rotating body, which rotates as a result of therotation of the motor being transmitted to the rotating body, and thelock bars, which are disposed on the rotating body and engage with thetake-up shaft to transmit to the take-up shaft the rotation of therotating body in the one direction about its axial line. The lock barsinclude the release pieces, and ordinarily the release pieces engagewith the push retention pieces of the sliders such that the lock barsare retained in the positions where the lock bars are disengaged fromthe take-up shaft. For this reason, the rotating body and the take-upshaft are ordinarily mutually relatively rotatable, and rotation arisingat the take-up shaft side is prevented from being transmitted to themotor.

Thus, the same effects that are obtained by the webbing take-up deviceof the first aspect are obtained.

In the clutch of the webbing take-up device based on this aspect, atleast one of the push retention pieces of the sliders and the releasepieces of the lock bars include retention portions that causepredetermined drag to arise with respect to the movement of the slidersaway from the lock bars when the rotating body is stopped. Consequently,even when the sliders try to move away from the lock bars due to intensevibration of the vehicle or the like during travel, this away movementis deterred by the predetermined drag resulting from the retentionportions, and the state of engagement between the push retention piecesof the sliders and the release pieces of the lock bars is maintained.Thus, the retention of the lock bars by the sliders is prevented frombeing inadvertently released, and erroneous linkage of the clutch isprevented.

In a fifth aspect of the invention, the retention portions of thewebbing take-up device of the fourth aspect are configured as slantedsurfaces that cause the lock bars to move a predetermined amount in thedirection in which the lock bars disengage from the take-up shaftcounter to the biasing force when the sliders move away from the lockbars.

In the webbing take-up device based on this aspect, slanted surfaces aredisposed on at least one of the push retention pieces of the sliders andthe release pieces of the lock bars. The slanted surfaces cause the lockbars to move a predetermined amount in the direction in which the lockbars disengage from the take-up shaft counter to the biasing force whenthe sliders move away from the lock bars. Thus, predetermined dragarises with respect to the movement of the sliders away from the lockbars, and erroneous linkage of the clutch is prevented.

A sixth aspect of the invention is a webbing take-up device comprising:a take-up shaft around which a webbing for restraining a passenger iswound such that the webbing can be taken up and pulled out; a motor; anda clutch that is mechanically intervened between the motor and thetake-up shaft, transmits the rotation of the motor to the take-up shaftto cause the take-up shaft to rotate, and cuts off the transmission ofrotation arising at the take-up shaft side to prevent that rotation frombeing transmitted to the motor, wherein the clutch includes a rotatingbody that is disposed coaxially with respect to the take-up shaft androtates as a result of the rotation of the motor being transmitted tothe rotating body, sliders that are configured to be relatively movablewithin a predetermined range with respect to the rotating body, and lockbars that are disposed on the rotating body and are always biased in adirection in which the lock bars disengage from the take-up shaft, andwhen the rotating body rotates in one direction about its axial line,the lock bars engage with the take-up shaft as a result of being pushedtoward the take-up shaft by the sliders and transmit to the take-upshaft the rotation of the rotating body in the one direction about itsaxial line, and when the rotating body rotates in the other directionabout its axial line, the lock bars are moved to and retained in thedisengaged positions by the biasing force as a result of the pushing bythe sliders being released.

The webbing take-up device based on this aspect is disposed with theclutch that transmits the rotation of the motor to the take-up shaft.The clutch includes the rotating body, which rotates as a result of therotation of the motor being transmitted to the rotating body, and thelock bars, which are disposed on the rotating body and engage with thetake-up shaft to transmit to the take-up shaft the rotation of therotating body in the one direction about its axial line. The lock barsare always biased in the direction in which they are disengaged from thetake-up shaft and are ordinarily retained in the positions where theyare disengaged from the take-up shaft. For this reason, the rotatingbody and the take-up shaft are ordinarily mutually relatively rotatable,and rotation arising at the take-up shaft side is prevented from beingtransmitted to the motor.

Thus, the same effects that are obtained by the webbing take-up deviceof the first aspect are obtained.

In the clutch of the webbing take-up device based on this aspect, thelock bars have a configuration where they are always biased in thedirection in which they are disengaged from the take-up shaft.Consequently, even when intense vibration arises in the vehicle duringtravel, for example, the lock bars are retained by the biasing force inthe positions where the lock bars are disengaged from the take-up shaft.Thus, the lock bars are prevented from inadvertently engaging with thetake-up shaft, and erroneous linkage of the clutch is prevented.

A seventh aspect of the invention is a webbing take-up devicecomprising: a take-up shaft around which a webbing for restraining apassenger is wound such that the webbing can be taken up and pulled out;a motor; and a clutch that is mechanically intervened between the motorand the take-up shaft, transmits the rotation of the motor to thetake-up shaft to cause the take-up shaft to rotate, and cuts off thetransmission of rotation arising at the take-up shaft side to preventthat rotation from being transmitted to the motor, wherein the clutchincludes a rotating body that is disposed coaxially with respect to thetake-up shaft and rotates as a result of the rotation of the motor beingtransmitted to the rotating body, a pair of sliders that are configuredto be relatively movable within a predetermined range with respect tothe rotating body, a spacer that couples together and synchronizes thepair of sliders, and a pair of lock bars that are disposed on therotating body and are ordinarily retained by the sliders in positionswhere the lock bars are disengaged from the take-up shaft, and when therotating body rotates in one direction about its axial line, theretention is released such that lock bars engage with the take-up shaftand transmit to the take-up shaft the rotation of the rotating body inthe one direction about its axial line, and when the rotating bodyrotates in the other direction about its axial line, the lock bars aremoved to and retained in the disengaged positions by the sliders.

The webbing take-up device based on this aspect is disposed with theclutch that transmits the rotation of the motor to the take-up shaft.The clutch includes the rotating body, which rotates as a result of therotation of the motor being transmitted to the rotating body, and thepair of lock bars, which are disposed on the rotating body and engagewith the take-up shaft to transmit to the take-up shaft the rotation ofthe rotating body in the one direction about its axial line. The lockbars are ordinarily retained by the pair of sliders in the positionswhere they are disengaged from the take-up shaft. For this reason, therotating body and the take-up shaft are ordinarily mutually relativelyrotatable, and rotation arising at the take-up shaft side is preventedfrom being transmitted to the motor.

Thus, the same effects that are obtained by the webbing take-up deviceof the first aspect are obtained.

In the clutch of the webbing take-up device based on this aspect, thepair of sliders that retain the pair of lock bars in the positions wherethe lock bars are disengaged from the take-up shaft are coupled togetherby the spacer and are synchronous.

Consequently, even when one of the sliders tries to relatively rotatewith respect to the rotating body (one of the lock bars) due to intensevibration of the vehicle or the like, the retention of the one lock barby the one slider is not released unless the other slider and the spacerrelatively rotate with respect to the rotating body. That is, in thisclutch, the retention of the lock bars by the sliders is not releasedunless the sliders and the spacer relatively rotate at the same timewith respect to the lock bars.

Thus, when the rotating body is stopped (i.e., when the motor isstopped), the pair of sliders are prevented from inadvertentlyrelatively rotating with respect to the pair of lock bars, and erroneouslinkage of the clutch is prevented.

In an eighth aspect of the invention, the clutch of the webbing take-updevice based on the seventh aspect includes a case and the spacerslidingly contacts the case.

In the webbing take-up device based on this aspect, the clutch includesa case, and the spacer that couples and synchronizes the pair of slidersis configured to slidingly contact the case. For this reason, becausefrictional force acts on the spacer, the pair of sliders and the spacercan be more reliably prevented from inadvertently relatively rotatingwith respect to the rotating body, that is, the pair of lock bars, anderroneous linkage of the clutch can be more reliably prevented.

EFFECTS OF THE INVENTION

As described above, the webbing take-up device pertaining to the presentinvention can not only transmit to a take-up shaft only rotation from amotor by a clutch but can also be configured simply and compactly.

Further, the webbing take-up device of the present invention can preventerroneous linkage of a clutch.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 An exploded perspective view showing the configuration ofrelevant portions of a clutch that is a configural member of a webbingtake-up device pertaining to an embodiment of the present invention.

FIG. 2 An exploded perspective view showing the configuration ofrelevant portions of the clutch that is a configural member of thewebbing take-up device pertaining to the embodiment of the presentinvention.

FIG. 3 A cross-sectional view showing the partial configuration of theclutch that is a configural member of the webbing take-up devicepertaining to the embodiment of the present invention.

FIG. 4A A side view showing a state where lock bars are retained insliders in the configuration of the clutch of the webbing take-up devicepertaining to the embodiment of the present invention.

FIG. 4B A side view showing a state where the lock bars are engaged witha ratchet in the configuration of the clutch of the webbing take-updevice pertaining to the embodiment of the present invention.

FIG. 5A A side view showing a state where a gear wheel and a rotor arecoupled together by spring pawls in the configuration of the clutch ofthe webbing take-up device pertaining to the embodiment of the presentinvention.

FIG. 5B A side view showing a state where the gear wheel and the rotorare relatively idling in the configuration of the clutch of the webbingtake-up device pertaining to the embodiment of the present invention.

FIG. 6A A side view showing a state where the lock bars are engaged withthe ratchet in the configuration of the clutch of the webbing take-updevice pertaining to the embodiment of the present invention.

FIG. 6B A side view showing a state where the lock bars allow relativerotation of the ratchet with respect to the rotor in a webbing take-updirection in the configuration of the clutch of the webbing take-updevice pertaining to the embodiment of the present invention.

FIG. 7A A side view showing a state where the lock bars are engaged withthe ratchet in the configuration of the clutch of the webbing take-updevice pertaining to the embodiment of the present invention.

FIG. 7B A side view showing a state where the lock bars are retained inthe sliders in the configuration of the clutch of the webbing take-updevice pertaining to the embodiment of the present invention.

FIG. 8 An exploded perspective view showing the configuration ofperipheral members including a motor that is a configural member of thewebbing take-up device pertaining to the embodiment of the presentinvention.

FIG. 9 An exploded perspective view showing the overall configuration ofthe webbing take-up device pertaining to the embodiment of the presentinvention.

FIG. 10 A perspective view showing the configuration of relevantportions of the webbing take-up device pertaining to the embodiment ofthe present invention.

FIG. 11A perspective view showing the overall configuration of thewebbing take-up device pertaining to the embodiment of the presentinvention.

FIG. 12 An exploded perspective view showing the overall configurationof a webbing take-up device pertaining to a second embodiment of thepresent invention.

FIG. 13 A perspective view showing the configuration of a clutch caseand a cover clutch that are configural members of the webbing take-updevice pertaining to the second embodiment of the present invention.

FIG. 14 An exploded perspective view showing the configuration ofrelevant portions of a clutch that is a configural member of the webbingtake-up device pertaining to the second embodiment of the presentinvention.

FIG. 15 An exploded perspective view showing the configuration ofrelevant portions of the clutch that is a configural member of thewebbing take-up device pertaining to the second embodiment of thepresent invention.

FIG. 16 A side view showing a coupling screw, a ratchet, and a washerthat are configural members of the webbing take-up device pertaining tothe second embodiment of the present invention.

FIG. 17 A side view showing the configuration of a rotor and slidersthat are configural members of the webbing take-up device pertaining tothe second embodiment of the present invention.

FIG. 18 A cross-sectional view showing the partial configuration of theclutch that is a configural member of the webbing take-up devicepertaining to the second embodiment of the present invention.

FIG. 19A A side view showing a state where lock bars are retained in thesliders in the configuration of the clutch of the webbing take-up devicepertaining to the second embodiment of the present invention.

FIG. 19B A side view showing a state where the lock bars are engagedwith the ratchet in the configuration of the clutch of the webbingtake-up device pertaining to the second embodiment of the presentinvention.

FIG. 20 A side view showing the configuration of the sliders and thelock bars of the webbing take-up device pertaining to the secondembodiment of the present invention.

FIG. 21A A side view showing a state where a gear wheel and the rotorare coupled together by spring pawls in the configuration of the clutchof the webbing take-up device pertaining to the second embodiment of thepresent invention.

FIG. 21B A side view showing a state where the gear wheel and the rotorare relatively idling in the configuration of the clutch that is aconfigural member of the webbing take-up device pertaining to the secondembodiment of the present invention.

FIG. 22 A side view showing the configuration of the sliders and aspacer of the webbing take-up device pertaining to the second embodimentof the present invention.

FIG. 23 An exploded perspective view showing the configuration of amotor and a motor gear portion of the webbing take-up device pertainingto the second embodiment of the present invention.

FIG. 24 A side view showing the configuration of installation and fixingof the motor and the motor gear portion of the webbing take-up devicepertaining to the second embodiment of the present invention.

FIG. 25A A side view showing a state where the lock bars are engagedwith the ratchet in the configuration of the clutch of the webbingtake-up device pertaining to the second embodiment of the presentinvention.

FIG. 25B A side view showing a state where the lock bars allow relativerotation of the ratchet with respect to the rotor in the webbing take-updirection in the configuration of the clutch of the webbing take-updevice pertaining to the second embodiment of the present invention.

FIG. 26A A side view showing a state where the lock bars are engagedwith the ratchet in the configuration of the clutch of the webbingtake-up device pertaining to the second embodiment of the presentinvention.

FIG. 26B A side view showing a state where the lock bars are retained inthe sliders in the configuration of the clutch of the webbing take-updevice pertaining to the second embodiment of the present invention.

FIG. 27A A side view showing a state where the lock bars are retained inpositions where they are disengaged from the ratchet in theconfiguration of the clutch of the webbing take-up device pertaining tothe second embodiment of the present invention.

FIG. 27B A side view showing a state where the lock bars are engagedwith the ratchet in the configuration of the clutch of the webbingtake-up device pertaining to the second embodiment of the presentinvention.

BEST MODES FOR IMPLEMENTING THE INVENTION First Embodiment

In FIG. 11, the overall configuration of a webbing take-up device 10pertaining to a first embodiment of the present invention is shown inperspective view. Further, in FIG. 10, the configuration of relevantportions of the webbing take-up device 10 is shown in perspective view.Moreover, in FIG. 9, the overall configuration of the webbing take-updevice 10 is shown in exploded perspective view.

The webbing take-up device 10 is disposed with a frame 12. The frame 12is configured by a substantially plate-like back plate 14 and a pair ofa leg plate 16 and a leg plate 18 that extend integrally from bothwidth-direction ends of the back plate 14. The frame 12 is attached to avehicle body as a result of the back plate 14 being fixed to the vehiclebody by unillustrated fastening means such as a bolt.

A take-up shaft 20 manufactured by die-casting or the like is rotatablydisposed between the pair of the leg plate 16 and the leg plate 18 ofthe frame 12. The take-up shaft 20 has a drum-like shape overall, and aproximal end portion of a webbing (not shown) formed in a long band-likeshape is coupled and fixed to the take-up shaft 20. When the take-upshaft 20 is rotated in one direction about its axial line (below, thisdirection will be called “the take-up direction”), the webbing is takenup in layers on the outer peripheral portion of the take-up shaft 20from its proximal end side, and when the webbing is pulled out from itsdistal end side, the webbing is pulled out while the take-up shaft 20rotates in the other direction about its axial line in accompanimenttherewith (below, the rotational direction of the take-up shaft 20 whenthe webbing is pulled out will be called “the pullout direction”).

One end side of the take-up shaft 20 penetrates the leg plate 18 andprotrudes outward of the frame 12. An unillustrated lock mechanism isdisposed on the side of the leg plate 18. The lock mechanism isconfigured to include an acceleration sensor and is linked to a lockplate 22 that spans the distance between the leg plate 16 and the legplate 18 and to a torsion bar 24 that is disposed in the axial centerportion of the take-up shaft 20. When the vehicle suddenly deceleratesor the like, one end of the torsion bar 24 is restrained via the lockplate 22 by the actuation of the lock mechanism so that energyabsorption is performed and the rotation of the take-up shaft 20 in thepullout direction is deterred.

The other end side of the take-up shaft 20 penetrates the leg plate 16and protrudes slightly outward of the frame 12. A coupling screw 21formed in a hexagonal column shape is coaxially and integrally coupledto the other end side of the take-up shaft 20.

Further, a clutch case 101 serving as a case configuring a clutch 100pertaining to the present embodiment is disposed on the outer side ofthe leg plate 16. The clutch case 101 is formed in a box-like shape by ametal material or the like (e.g., an aluminum alloy, etc.) and openstoward the side opposite of the leg plate 16. A cover clutch 102comprising an iron plate or the like and serving as a case is disposedon the open side of the clutch case 101. The clutch case 101 and thecover clutch 102 are integrally fixed to the leg piece 16 by a screw291.

A circular through hole 106 is formed coaxially with the take-up shaft20 in the center portion of the bottom wall of the clutch case 101, andthe coupling screw 21 passes through the through hole 106. Further, thesite in the vicinity of the through hole 106 protrudes slightly in acircular fashion toward the side opposite of the leg piece 16, and aring-like sliding surface 108 is formed. Moreover, a circularcylindrical bushing support portion 110 that protrudes toward the sideopposite of the leg piece 16 is formed in the hole edge portion of thethrough hole 106. A bushing 112 (see FIG. 1 and FIG. 2) formed in aring-like shape by a resin material or the like is supported on thebushing support portion 110.

A clutch gear portion 28 is disposed inside the clutch case 101. Theclutch gear portion 28 is disposed with a worm gear 34. The axis of theworm gear 34 is disposed in a state where it is perpendicular to thetake-up shaft 20, end portions of the worm gear 34 are supported on theclutch case 101 via bushes 36 and 37, and one end side of the worm gear34 is disposed protruding outward from the clutch case 101. Further, asteel ball 38 is housed in a bearing portion of the clutch case 101 thatsupports the distal end portion of the worm gear 34, the steel ball 38contacts the distal end portion of the worm gear 34, and an adjust screw40 is screwed into the bearing portion. The adjust screw 40 pushes thesteel ball 38 at its distal end portion to cause the steel ball 38 to bepressed against the distal end of the worm gear 34. Thus, displacementin the axial direction of the worm gear 34 is regulated(thrust-adjusted). It will be noted that the steel ball 38 may also beconfigured such that it is formed integrally on the distal end portionof the adjust screw 40 (such that the distal end portion of the adjustscrew 40 is formed in a spherical shape). A clutch body portion 114 thatconfigures the clutch 100 pertaining to the present embodiment isdisposed above the worm gear 34.

Here, in FIG. 1 and FIG. 2, the configuration of the clutch body portion114 is shown in exploded perspective view.

As shown in these drawings, the clutch body portion 114 is disposed witha gear wheel 116. The gear wheel 116 is formed in a ring-like shape by aresin material or the like, is disposed coaxially with the take-up shaft20, and worm wheel teeth 118 are formed on the outer peripheral portionof the gear wheel 116. The worm wheel teeth 118 mesh with theabove-mentioned worm gear 34. Further, plural (six in the presentembodiment) circumferential-direction load receiving portions 120 areformed on the inner peripheral portion of the gear wheel 116 at constantintervals along the radial direction of the gear wheel 116. Thecircumferential-direction load receiving portions 120 correspond tolater-described spring pawls 182 of a ring 176. Moreover, plural (six inthe present embodiment) baffle concave portions 122 are formed on theend surface of one axial-line direction side (the side in the directionof arrow A in FIG. 1 and FIG. 2) of the gear wheel 116 at constantintervals along the circumferential direction of the gear wheel 116. Thebaffle concave portions 122 correspond to later-described baffle pawls180 of the ring 176.

A rotor 124 formed in a discoid shape by a metal material or the like(e.g., zinc aluminum alloy, etc.) is disposed coaxially with the gearwheel 116 inside the gear wheel 116. The rotor 124 includes a bottomedcircular cylindrical body portion 126 and a flange portion 128 thatprotrudes in the radial direction at one axial-line direction side (theside in the direction of arrow B in FIG. 1 and FIG. 2) of the bodyportion 126.

Plural outer teeth 130 are formed on the outer peripheral portion of thebody portion 126 at equidistant intervals along the circumferentialdirection of the body portion 126. Side walls of the outer teeth 130 onone side (the side in the direction of arrow C in FIG. 1 and FIG. 2)along the circumferential direction of the body portion 126 slant withrespect to the circumferential direction of the body portion 126, andside walls of the outer teeth 130 on the other side (the side in thedirection of arrow D in FIG. 1 and FIG. 2) along the circumferentialdirection of the body portion 126 are formed parallel along the radialdirection of the body portion 126 (in other words, the cross-sectionalshapes of the outer teeth 130 are trapezoidal). The outer teeth 130correspond to the later-described spring pawls 182 of the ring 176.

A substantially circular cylindrical housing portion 132 is formedcoaxially in the center portion of the bottom wall of the body portion126. A ring-like support shaft portion 133 protrudes coaxially on oneaxial-line direction side (the side in the direction of arrow A in FIG.1 and FIG. 2) of the housing portion 132. The support shaft portion 133is supported in a circular hole 135 formed in the cover clutch 102 suchthat the support shaft portion 133 can freely rotate via alater-described rotation support portion 175 of a holder 170. Further,the previously mentioned bushing 112 is fitted, such that it can freelyrotate, in the other axial-line direction side (the side in thedirection of arrow B in FIG. 1 and FIG. 2), and the other axial-linedirection side of the housing portion 132 is supported, such that it canfreely rotate, on the clutch case 101 via the bushing 112. Thus, thebody portion 126 (the rotor 126) is configured to be rotatable about itsown axial line.

A ratchet 134 formed in a substantially ring-like shape by a steel plateor the like is housed inside the housing portion 132 of the body portion126. Outer teeth 136 that are ratchet teeth are formed on the outerperipheral portion of the ratchet 134. Further, a through hole (couplinghole) 138 that has a cross-sectionally hexagonal shape is formed in theaxial center portion of the ratchet 134, and the previously mentionedcoupling screw 21 is integrally (such that relative rotation isimpossible) coupled to the ratchet 134 with respect to about its axialline in a state where the coupling screw 21 has been passed through thethrough hole 138. Thus, the ratchet 134 and the take-up shaft 20 areconfigured to rotate integrally via the coupling screw 21.

It will be noted that one axial-line direction side (the side in thedirection of arrow B in FIG. 1 and FIG. 2) of the ratchet 134 slidablyabuts against the previously mentioned bushing 112. Further, a washer140 comprising a resin material or the like is attached to the otheraxial-line direction end (the side in the direction of arrow A in FIG. 1and FIG. 2) of the ratchet 134. The washer 140 slidably abuts againstthe ring-like bottom wall of the housing portion 132, so thatdisplacement along the axial line direction of the ratchet 138 isregulated.

A pair of guide holes 142 that are curved along the circumferentialdirection of the body portion 126 is formed in the bottom wall of thebody portion 126 at the radial-direction outer side of the housingportion 132. Sliders 144 that are formed by a resin material or the likein substantially block-like shapes and are curved along thecircumferential direction of the body portion 126 are slidably attachedto the guide holes 142. The pair of sliders 144 is retained (guided) bythe inner peripheral surface of the body portion 126 and by the outerperipheral surface of the housing portion 132 and is configured to berelatively movable with respect to the body portion 126 (the rotor 124)within a predetermined range along the guide holes 142.

Sliding pieces 146 protrude from one side (the side in the direction ofarrow A in FIG. 1 and FIG. 2) of the sliders 144 and, as shown in FIG.3, abut against the cover clutch 102. Further, retainers 148 aredisposed on the side of the sliders 144 opposite of the sliding pieces146. The retainers 148 are narrow metal pieces having elasticity and arebent in substantial “<” shapes. The retainers 148 are integrally coupledto the sliders 144 as a result of coupling portions 150 disposed inlongitudinal-direction center portions of the retainers 148 being fittedinto coupling holes 152 formed in the sliders 144, and are elasticallydeformed a predetermined amount as a result of bothlongitudinal-direction end portions of the retainers 148 being pushedagainst the previously mentioned sliding surface 108 of the clutch case101.

For this reason, the sliding pieces 146 of the sliders 144 are pushedagainst the cover clutch 102 by the elastic force of the retainers 148,and predetermined frictional force is imparted to the movement (relativemovement with respect to the rotor 124) of the sliders 144 along theguide holes 142. For this reason, when the rotor 124 rotates, thesliders 144 are retained in the case (the clutch case 101 and the coverclutch 102) temporarily by the frictional force acting on bothlongitudinal-direction end portions of the retainers 148 and the slidingpieces 146 and relatively move within a predetermined range along theguide holes 142 with respect to the rotor 124.

Further, a push retention piece 145 is formed on one curve-direction endportion (the end portions at the side in the direction of arrow C inFIG. 1 and FIG. 2) of each of the sliders 144. The push retention pieces145 correspond to a pair of lock bars 154.

Each of the lock bars 154 is formed in a substantial “<” shape by asteel plate or the like, is disposed on one curve-direction end side ofeach of the sliders 144, and is disposed with a ring-like bearingportion 156. The bearing portions 156 are supported, such that they canfreely rotate, by circular columnar support shafts 158 that protrudefrom the bottom wall of the body portion 126. A coupling piece 160protrudes on the side (the side in the direction of arrow C in FIG. 1and FIG. 2) of each of the bearing portions 156 opposite from thesliders 144. The coupling pieces 160 rotate about the support shafts 158together with the bearing portions 156, whereby the distal end portionsof the coupling pieces 160 penetrate hole portions 162 formed in thehousing portion 132 of the rotor 124 and mesh with the previouslymentioned outer teeth 136 of the ratchet 134. Further, the couplingpieces 160 are always biased in the direction in which they mesh withthe outer teeth 136 (the ratchet 134) by the biasing force of torsioncoil springs 164. It will be noted that the torsion coil springs 164 aresupported by circular columnar support shafts 166 that protrude from thebottom wall of the body portion 126 of the rotor 124.

Release pieces 168 that correspond to the previously mentioned pushretention pieces 145 protrude from the sliders 144 side (the side in thedirection of arrow D in FIG. 1 and FIG. 2) of the bearing portions 156.The end portions of the release pieces 168 facing the sliders 144 areformed as slanted surfaces that are slanted with respect to the movingdirection of the sliders 144 (the direction of arrow C and the directionof arrow D in FIG. 1 and FIG. 2).

Here, as shown in FIG. 4A and FIG. 4B, when the rotor 124 relativelymoves with respect to the sliders 144, the lock bars 154 move within apredetermined range toward and away from the sliders 144, and in a statewhere the lock bars 154 are close to the sliders 144 (the state shown inFIG. 4A), the release pieces 168 of the lock bars 154 enter the innersides (ratchet 134 sides) of the push retention pieces 145 of thesliders 144, whereby the release pieces 168 are retained in disengagedpositions counter to the biasing force of the torsion coil springs 164.In this state, the coupling pieces 160 of the lock bars 154 move awayfrom the ratchet 134.

On the other hand, in a state where the lock bars 154 have moved awayfrom the sliders 144 (the state shown in FIG. 4B), the release pieces168 of the lock bars 154 release the retention by the push retentionpieces 145 of the sliders 144. In this state, the coupling pieces 160 ofthe lock bars 154 are moved toward the ratchet 134 (engagementpositions) by the biasing force of the torsion coil springs 164, and thedistal end portions of the coupling pieces 160 mesh with the outer teeth136.

It will be noted that, in the clutch body portion 114 pertaining to thepresent embodiment, the sliders 144 are ordinarily disposed close to thelock bars 154. Consequently, the lock bars 154 are ordinarily retainedin the disengaged positions (the state shown in FIG. 4A) as a result ofthe release pieces 168 being retained by the push retention pieces 145of the sliders 144.

A holder 170 formed in a ring-like shape by a resin material or the likeis disposed at the side (the side in the direction of arrow A in FIG. 1and FIG. 2) opposite from the rotor 124 via the lock bars 154. Theholder 170 is disposed with a ring-like body portion 172 and a pair ofretention pawls 174 disposed on the outer peripheral portion of the bodyportion 172. The body portion 172 regulates displacement of the lockbars 154 in the axial line direction with respect to the support shafts158 (the rotor 124), and the pair of retention pawls 174 regulatedisplacement of the torsion coil springs 164 in the axial line directionwith respect to the support shafts 166 (the rotor 124).

Further, the support shaft portion 133 of the rotor 124 penetrates acircular hole 173 formed in the center portion of the body portion 172.A rotation support portion 175 that protrudes slightly in a circularcylindrical shape toward the side opposite from the rotor 124 (towardthe cover clutch 102) is disposed on the hole edge portion of thecircular hole 173, and the support shaft portion 133 of the rotor 124 issupported, such that it can freely rotate, in the circular hole 135 ofthe cover clutch 102.

A ring 176 comprising a metal material (e.g., SUS, etc.) havingelasticity is disposed at the radial-direction outer side of the holder170 and on one axial-line direction side (the side in the direction ofarrow A of FIG. 1 and FIG. 2) of the rotor 124. The ring 176 is disposedwith a cover portion 178 formed in a ring shape. Plural (six in thepresent embodiment) baffle pawls 180 that protrude outward in the radialdirection of the cover portion 178 are integrally formed on the outerperipheral portion of the cover portion 178. The baffle pawls 180 fitinto the previously mentioned baffle concave portions 122 of the gearwheel 116. Thus, the ring 176 is integrally coupled to the gear wheel116 in the circumferential direction of the gear wheel 116.

Moreover, plural (six in the present embodiment) spring pawls 182 thatare formed in narrow plate shapes having elasticity (spring-ness) areintegrally formed on the outer peripheral portion of the cover portion178 at constant intervals along the circumferential direction of thecover portion 178. The proximal end portions of the spring pawls 182 areintegrally connected to the cover portion 178, thelongitudinal-direction intermediate portions of the spring pawls 182 arebent slightly toward the radial-direction inner side of the coverportion 178, and the distal end portions of the spring pawls 182 arebent toward the radial-direction outer side of the cover portion 178, sothat, overall, the spring pawls 182 curve along the circumferentialdirection of the cover portion 178.

As shown in FIG. 5A, the spring pawls 182 are disposed along thecircumferential direction of the rotor 124 and the gear wheel 116between the outer teeth 130 of the rotor 124 and the inner peripheralsurface of the gear wheel 116, and the inner side portions of the springpawls 182 are pushed against the outer teeth 130 of the rotor 124 by theelastic force of the spring pawls 182. Thus, the ring 176 is integrallyretained on the rotor 124.

Further, the outer side portions of the spring pawls 182 are engagedwith the inner peripheral surface of the gear wheel 116, and the gearwheel 116 is supported on the rotor 124 via the spring pawls 182. Inthis state, the movement of the gear wheel 116 in the axial linedirection is regulated by the baffle pawls 180 of the ring 176 and theflange portion 128 of the rotor 124. Moreover, in this state, thesliders 144, the lock bars 154, the torsion coil springs 164, and theholder 170 are prevented from coming off the rotor 124 by the coverportion 178 of the ring 176, and these configural members are retainedin predetermined installation positions.

Moreover, the distal end portions of the spring pawls 182 enter thevalley portions between the outer teeth 130 and abut against one sidewall of the outer teeth 130 (side walls at the sides formed parallelalong the radial direction of the body portion 126), and the proximalend portions of the spring pawls 182 abut against the previouslymentioned circumferential-direction load receiving portions 120 of thegear wheel 116. Thus, the gear wheel 116 and the rotor 124 areintegrally coupled together (their relative rotation is regulated) bythe spring pawls 182 with respect to their circumferential direction,and when the gear wheel 116 rotates, the gear wheel 116 and the rotor124 basically integrally rotate.

In this case, the rotational force of the gear wheel 116 in the take-updirection is transmitted to the proximal end portions of the springpawls 182 via the circumferential-direction load receiving portions 120and is transmitted to the outer teeth 130 of the rotor 124 from thedistal end portions of the spring pawls 182, such that the gear wheel116 receives along the circumferential direction the load acting thereonfrom the spring pawls 182 via the circumferential-direction loadreceiving portions 120 (the direction in which the gear wheel 116receives the load from the spring pawls 182 is set along the rotationaldirection thereof).

Moreover, in this case, because the spring pawls 182 are metal pieceshaving elasticity, the coupling about the axial line between the gearwheel 116 and the rotor 124 by the spring pawls 182 is released as longas the rotational force arising due to the relative rotation of the gearwheel 116 with respect to the rotor 124 is of a size sufficient forcausing the distal end portions of the spring pawls 182 to escape fromthe valley portions between the outer teeth 130 counter to the springforce (biasing force) of the spring pawls 182, and for this reason,relative rotation between the gear wheel 116 and the rotor 124 becomespossible (see FIG. 5B).

Further, the rotational force of the gear wheel 116 in the pulloutdirection is transmitted to the baffle pawls 180 of the ring 176 via thebaffle concave portions 122 and is transmitted from the distal endportions of the spring pawls 182 of the ring 176 to the outer teeth 130of the rotor 124.

A spacer 184 formed in a ring shape by a resin material or the like isdisposed on the side of the ring 176 opposite from the rotor 124 (theside in the direction of arrow A in FIG. 1 and FIG. 2). The spacer 184is sandwiched between the ring 176 and the cover clutch 102 and isconfigured such that relative rotation is impossible with respect to thering 176 about the axial line thereof. The spacer 184 prevents the metalring 176 from directly sliding against the cover clutch 102 and ensuresthat the relative rotation of the ring 176 (the clutch body portion 114)with respect to the cover clutch 102 is smooth.

The clutch 100 having the above-described configuration is configuredsuch that the gear wheel 116 of the clutch body portion 114 rotates whenthe worm gear 34 of the clutch gear portion 28 rotates, and the clutchbody portion 114 and the clutch gear portion 28 are integrally assembledinto a single case (the clutch case 101 and the cover clutch 102), sothat, overall, the clutch 100 is unitized.

As shown in FIG. 9, a spring complete 42 is disposed on the side of thecover clutch 102. The spring complete 42 houses a spiral spring (notshown) inside. The end portion of the spiral spring at the outer side inthe spiral direction is latched to the case body, and the end portion ofthe spiral spring at the inner side in the spiral direction is latchedto the distal end of the coupling screw 21 penetrating the clutch bodyportion 114, and the spiral spring biases the take-up shaft 20 in thetake-up direction.

Further, a motor 44 and a motor gear portion 46 are disposed below thetake-up shaft 20 between the leg plate 16 and the leg plate 18.

Here, in FIG. 8, the configurations of the motor 44 and the motor gearportion 46 are shown in perspective view.

The motor 44 and the motor gear portion 46 are disposed with a housing48. The motor 44 is disposed on one side of the housing 48, and themotor gear portion 46 is disposed on the other side of the housing 48.The motor 44 is fixed to the one side of the housing 48 in a state wherethe distal end side (the output side) of a rotating shaft 50 faces thehousing 48, and the distal end (the output side) of the rotating shaft50 protrudes toward the other side of the housing 48 (the side of themotor gear portion 46). Further, a base plate 54, to which an electricalharness 52 for driving the motor is connected, is attached to thetrailing end side of the motor 44. The electrical harness 52 isconnected to the base plate 54, and the connected portion of theelectrical harness 52 is connected by a crimp-style terminal structureto a power supply terminal 56 disposed on the body portion of the motor44. It will be noted that the connected portion of the electricalharness 52 and the power supply terminal 56 may also be configured suchthat they are connected by solder or the like.

Moreover, the motor 44 is covered by a cover motor 58. Pawl portions 60are disposed on the cover motor 58, and the pawl portions 60 fittogether and latch with pawl receiving protrusions 62 disposed on thehousing 48, whereby the cover motor 58 is fixed to the housing 48.

Further, here, a first concave portion 64 is disposed in the cover motor58, and a convex portion 66 that can fit into the first concave portion64 is disposed on the base plate 54 in correspondence to the firstconcave portion 64. Moreover, a second concave portion 68 into which theconvex portion 66 can fit is disposed on the motor 44 in correspondenceto the convex portion 66 of the base plate 54.

That is, the convex portion 66 is fitted into the second concave portion68 to position the motor 44 with respect to the base plate 54, theconvex portion 66 is fitted into the first concave portion 64 toposition the base plate 54 with respect to the cover motor 58, and thepawl portions 60 are fitted together and latched with the pawl receivingprotrusions 62 to attach and fix the cover motor 58 to the housing 48,whereby the installation position about the axis of the motor 44 withrespect to the housing 48 is unambiguously defined.

Moreover, the electrical harness 52 for driving the motor is derivedfrom the trailing end portion of the cover motor 58 facing the backplate 14 of the frame 12 opposite from the output side of the motor 44.Further, the derived portions of the electrical harness 52 of the covermotor 58 are waterproofed by rubber caps 70.

A pinion 72 configuring plural spur teeth of the motor gear portion 46is attached to the distal end of the rotating shaft 50 of the motor 44protruding toward the other side of the housing 48 (the side of themotor gear portion 46). Further, a gear 74 and a gear 76, each of whichconfigures drive force transmitting means formed as outer-toothed spurgears, are housed in the motor gear portion 46 in a state where they aremeshed with each other. The gear 74 and the gear 76 are disposed in astate where their axes are parallel to the rotating shaft 50 of themotor 44. The gear 74 meshes with the pinion 72, and the gear 76, whichserves as a final spur gear, is detachably coupled to the previouslymentioned one end portion of the worm gear 34 protruding outward fromthe clutch case 101 of the clutch gear portion 28. For this reason, whenthe motor 44 is driven, drive force is transmitted via the pinion 72,the gear 74, and the gear 76, and the worm gear 34 is rotated.

Further, the pinion 72, the gear 74, and the gear 76 are covered by acover gear 78 attached to the housing 48. Pawl portions 80 are disposedon the cover gear 78, and the pawl portions 80 fit together andhook-and-lock with pawl receiving portions 82 disposed on the housing48, whereby the cover gear 78 is fixed to the housing 48.

In this manner, the motor 44 and the motor gear portion 46 are bothintegrally assembled to the single housing 48, so that, overall, theyare unitized.

As for the motor 44 and the motor gear portion 46 having the aboveconfiguration, an attachment stay 84 integrally disposed on the housing48 is detachably attached by screws 86 to the clutch case 101 (i.e., theframe 12) housing the clutch body portion 114 and the clutch gearportion 28. In a state where the housing 48 is attached to the clutchcase 101 (the frame 12), the rotating shaft 50 of the motor 44 isorthogonal to the take-up shaft 20 and the output side of the motor 44faces the side of the frame 12 opposite from the back plate 14, and themotor 44 is positioned between the pair of the leg plate 16 and the legplate 18 and directly below the take-up shaft 20.

Further, here, the motor 44 and the motor gear portion 46 having thepreviously mentioned configuration are configured such that the gear 76serving as the final spur gear of the motor gear portion 46 is separablycoupled to the clutch 26 and the worm gear 34 of the clutch gear portion28 and the attachment stay 84 is detachably attached by the screws 86 tothe clutch case 101, so that by removing the screws 86 and removing theattachment stay 84 from the clutch case 101, the motor 44 and the motorgear portion 46 can be independently separated from the clutch case 101(the frame 12) in an assembled state.

Moreover, the motor 44 mentioned above is configured to be actuated onthe basis of a detection signal of a forward monitoring device or thelike, for example.

Next, the action of the present embodiment will be described.

In the webbing take-up device 10 having the above-describedconfiguration, the sliders 144 of the clutch body portion 114 areordinarily disposed close to the lock bars 154, as shown in FIG. 4A.Consequently, the release pieces 168 of the lock bars 154 are ordinarilyretained by the push retention pieces 145 of the sliders 144, and thecoupling pieces 160 of the lock bars 154 are separated from the outerteeth 136 of the ratchet 134. For this reason, the ratchet 134 (thetake-up shaft 20) is free to relatively rotate with respect to the rotor124.

Consequently, when a passenger is seated in the seat of the vehicle andpulls out the webbing stored in the webbing take-up device 10, thewebbing is pulled out while the take-up shaft 20 rotates in the pulloutdirection. Thus, the passenger places the webbing around his/her bodyand causes a tongue plate disposed on the webbing, for example, toengage with a buckle device, whereby the passenger can wear the webbingaround his/her body.

When an obstacle is present in front of the vehicle while the vehicle istraveling and the distance between the vehicle and the obstacle (thedistance from the vehicle to the obstacle) comes within a predeterminedrange, the driving of the motor 44 is started and the rotating shaft 50is suddenly rotated.

When the rotating shaft 50 of the motor 44 is rotated, the rotationalforce is transmitted to the gear wheel 116 of the clutch body portion114 via the pinion 72, the gear 74, and the gear 76 of the motor gearportion 46 and the worm gear 34 of the clutch gear portion 28, and thegear wheel 116 is suddenly rotated in the take-up direction. Therotation of the gear wheel 116 in the take-up direction is transmittedto the proximal end portions of the spring pawls 182 of the ring 176 viathe circumferential-direction load receiving portions 120 and istransmitted to the outer teeth 130 of the rotor 124 from the distal endportions of the spring pawls 182, and the rotor 124 is suddenly rotatedin the take-up direction.

At this time, because the sliders 144 are retained in the case (theclutch case 101 and the cover clutch 102) by frictional force acting onthe sliding pieces 146 and the retainers 148, the rotor 124 relativelymoves within a predetermined range with respect to the sliders 144, andthe lock bars 154 supported on the rotor 124 move away from the sliders144.

For this reason, the retention of the release pieces 168 by the pushretention pieces 145 is released, the coupling pieces 160 of the lockbars 154 are moved toward the ratchet 134 by the biasing force of thetorsion coil springs 164, and the distal end portions of the couplingpieces 160 mesh with the outer teeth 136 of the ratchet 134 (see arrow Ein FIG. 4B). Thus, the rotation of the rotor 124 in the take-updirection is transmitted to the ratchet 134 via the lock bars 154, andthe ratchet 134 is suddenly rotated in the take-up direction. Becausethe ratchet 134 is integrally coupled to the take-up shaft 20, thetake-up shaft 20 is suddenly rotated in the take-up direction togetherwith the ratchet 134.

Thus, the webbing is taken up on the take-up shaft 20, slight loosenessof the webbing known as “slack” is eliminated and the restraining forceof the webbing with respect to the body of the passenger is improved, sothat even if the passenger thereafter performs the operation of suddenvehicular braking (sudden braking) and the vehicle suddenly decelerates,the webbing reliably holds the body of the passenger.

Moreover, in a state where the “slack” has been eliminated as describedabove, the body of the passenger becomes an obstacle, so that basicallyno more of the webbing becomes able to be taken up on the take-up shaft20. For this reason, a load equal to or greater than a predeterminedvalue acts on the take-up shaft 20 from the webbing, and as a result, aload equal to or greater than a predetermined value acts on the rotor124 via the ratchet 134 and the lock bars 154. When a load equal to orgreater than a predetermined value acts on the rotor 124, as shown inFIG. 5A and FIG. 5B, the spring pawls 182 become elastically deformed,the distal end portions of the spring pawls 182 escape from the valleyportions between the outer teeth 130 of the rotor 124, and relativeidling between the gear wheel 116 and the rotor 124 becomes possible (a“load limiter mechanism”; see arrow F in FIG. 5B).

Thus, the take-up shaft 20 coupled to the rotor 124 via the ratchet 134and the lock bars 154 can be prevented from being rotated in the take-updirection with a force more than necessary by the driving force of themotor 44, and the webbing can be prevented from tightening around thebody of the passenger with a force more than necessary.

Moreover, in this state, because the outer teeth 136 of the ratchet 134are formed as ratchet teeth, as shown in FIGS. 6A and 6B, when theratchet 134 (the take-up shaft 20) tries to relatively rotate in thetake-up direction with respect to the rotor 124 (see arrow H in FIG.6B), the lock bars 154 jump over the outer teeth 136 of the ratchet 134(see arrow G in FIG. 6B) and allow the relative rotation of the ratchet134 (the take-up shaft 20) in the take-up direction with respect to therotor 124. Thus, as described above, when, for example, a collision ofthe vehicle cannot be avoided in a state where the “slack” has beeneliminated, it is also possible to cause the take-up shaft 20 to beforcibly rotated in the take-up direction by a separate pretensionermechanism or the like. In this case, the restraining force of thewebbing on the body of the passenger can be further raised, and injuryto the passenger in the event of a vehicle collision can be kept to aminimum.

When the danger of such a vehicle collision has been avoided, therotating shaft 50 of the motor 44 is reversely rotated. The rotationalforce of the rotating shaft 50 is transmitted to the gear wheel 116 ofthe clutch body portion 114 via the pinion 72, the gear 74, and the gear76 of the motor gear portion 46 and the worm gear 34 of the clutch gearportion 28, and the gear wheel 116 is suddenly rotated in the pulloutdirection (see arrow D in FIG. 7A).

The rotation of the gear wheel 116 in the pullout direction istransmitted to the baffle pawls 180 of the ring 176 via the baffleconcave portions 122 of the gear wheel 116 and is transmitted to theouter teeth 130 of the rotor 124 from the distal end portions of thespring pawls 182 of the ring 176, and the rotor 124 is suddenly rotatedin the pullout direction.

At this time, because the sliders 144 are retained in the case (theclutch case 101 and the cover clutch 102) by frictional force acting onthe sliding pieces 146 and the retainers 148, the rotor 124 relativelymoves within a predetermined range with respect to the sliders 144, andthe lock bars 154 supported on the rotor 124 move toward the sliders144.

For this reason, the push retention pieces 145 of the sliders 144 pushthe slanted end surfaces of the release pieces 168 of the lock bars 154,whereby the release pieces 168 are moved toward the ratchet 134 counterto the biasing force of the torsion coil springs 164 (see arrow J inFIG. 7B), and the coupling pieces 160 of the lock bars 154 move awayfrom the outer teeth 136 of the ratchet 134. Moreover, when the lockbars 154 move toward the sliders 144, the release pieces 168 of the lockbars 154 enter the inner sides (toward the ratchet 134) of the pushretention pieces 145 of the sliders 144 so that the lock bars 154 areretained in the disengaged positions (the state shown in FIG. 7B). Thus,the rotor 124 and the ratchet 134 again become relatively rotatable sothat free rotation of the take-up shaft 20 becomes possible.

Here, the clutch 100 of the webbing take-up device 10 has a simpleconfiguration where, as described above, the sliders 144 of the clutchbody portion 114 are caused to be retained in the case (the clutch case101 and the cover clutch 102) by frictional force, whereby the sliders144 and the lock bars 154 are caused to relatively move and the lockbars 154 are caused by this relative movement to move to the positionswhere the lock bars 154 engage with or disengage from the ratchet 134.Consequently, the overall configuration of the clutch 100 can be madesignificantly compact (in particular, thinned) in comparison to aconfiguration where a pawl is moved using an inertial disk that is largeand has a certain weight as in a conventional clutch. Thus, the overallconfiguration of the webbing take-up device 10 can be made compact.

Moreover, in the clutch 100 of the webbing take-up device 10, the clutchbody portion 114 does not have a configuration where it is supported onthe take-up shaft 20 but has a configuration where it is supported onthe case (the clutch case 101 and the cover clutch 102). That is, theclutch body portion 114 is supported, such that it can freely rotate, onthe case (the clutch case 101 and the cover clutch 102) as a result ofthe support shaft portion 133 disposed on one axial-line direction sideof the housing portion 132 of the rotor 124 being supported, such thatit can freely rotate, in the circular hole 135 of the cover clutch 102via the rotation support portion 175 of the holder 170 and as a resultof the other axial-line direction side of the housing portion 132 beingsupported, such that it can freely rotate, on the clutch case 101 viathe bushing 112. Consequently, in the webbing take-up device 10, thetake-up shaft 20 can rotate without relation to the clutch body portion114 at times other than the state where the rotor 124 and the ratchet134 (the take-up shaft 20) are coupled together by the lock bars 154(when the vehicle suddenly decelerates, etc.) Thus, smooth rotation ofthe take-up shaft 20 is assured, and the ease with which the webbing canbe pulled out and taken up during ordinary use is improved.

Further, in the clutch 100 of the webbing take-up device 10, thecircumferential-direction load receiving portions 120 are disposed onthe gear wheel 116 of the clutch body portion 114, and when rotationalforce in the take-up direction is transmitted from the gear wheel 116 tothe rotor 124, the load acting on the gear wheel 116 from the springpawls 182 acts along the circumferential direction of the gear wheel 116via the circumferential-direction load receiving portions 120. For thisreason, it is not necessary to raise the rigidity of the gear wheel 116for a load acting along the radial direction of the gear wheel 116 fromthe spring pawls 182 during this rotational force transmission.

Moreover, in the clutch 100, the spring pawls 182 have a configurationwhere, when a load equal to or greater than a predetermined value actson the rotor 124, the spring pawls 182 become elastically deformed tocause their distal end portions to escape from the outer teeth of therotor and cut off the transmission of rotation between the gear wheel116 and the rotor 124. That is, the spring pawls 182 have aconfiguration where the operation of a “load limiter mechanism” aspreviously mentioned is performed between the rotor 124 and the springpawls 182, and a load along the radial direction does not act on thegear wheel 116. Consequently, in this respect also, it is not necessaryto raise the rigidity of the gear wheel 116. Consequently, in the clutch100, the gear wheel 116 can be molded thinly or molded by resin or thelike. Thus, the clutch 100 can be made compact and lightweight.

Moreover, in the clutch 100 of the webbing take-up device 10, the ring176 of the clutch body portion 144 integrally includes the cover portion178, which retains the gear wheel 116, the sliders 144, the lock bars154, the torsion coil springs 164 and the holder 170 in predeterminedinstallation positions, and the spring pawls 182 for the previouslymentioned “load limiter mechanism”. Moreover, the ring 176 has aconfiguration where it is integrally retained on the rotor 124 by theelastic force of the spring pawls 182. That is, in the clutch bodyportion 144, the gear wheel 116, the sliders 144, the lock bars 154, thetorsion coil springs 164 and the holder 170 are assembled inpredetermined installation positions, and the ring 176 is caused to beretained on the rotor 124 by the elastic force of the spring pawls 182,so that the clutch configural members can be integrally temporarily held(sub-assembled). Thus, the installability such as when the clutch bodyportion 114 is installed in the case (the clutch case 101 and the coverclutch 102) is significantly improved, and the productivity of thewebbing take-up device 10 is improved.

As described above, the webbing take-up device 10 pertaining to thepresent embodiment can not only transmit to the take-up shaft 20 justthe rotation from the motor 44 by the clutch 100, but also can beconfigured simply and compactly.

It will be noted that in the above-described embodiment, although thewebbing take-up device was configured such that the rotation of therotating shaft 50 of the motor 44 was transmitted to the take-up shaft20 by the clutch 100 to cause the take-up shaft 20 to rotate in thewebbing take-up direction, the webbing take-up device may also beconfigured such that the rotation of the rotating shaft 50 of the motor44 is transmitted to the take-up shaft 20 by the clutch to cause thetake-up shaft 20 to rotate in the webbing pullout direction.

Second Embodiment

The overall configuration of a webbing take-up device 210 pertaining toa second embodiment of the present invention is the same as that shownin FIG. 11 of the first embodiment, so illustration thereof will beomitted. Further, the configurations of relevant portions of the webbingtake-up device 210 are the same as those shown in FIG. 10 of the firstembodiment, so illustration thereof will be omitted. In FIG. 12, theoverall configuration of the webbing take-up device 210 of the presentembodiment is shown in exploded perspective view.

The webbing take-up device 210 is disposed with a frame 212. The frame212 is configured by a substantially plate-like back plate 214 and apair of a leg plate 216 and a leg plate 218 that extend integrally fromboth width-direction ends of the back plate 214. The frame 12 isattached to a vehicle body as a result of the back plate 214 being fixedto the vehicle body by unillustrated fastening means such as a bolt.

A take-up shaft 220 manufactured by die-casting or the like is rotatablydisposed between the pair of the leg plate 216 and the leg plate 218 ofthe frame 212. The take-up shaft 220 has a drum-like shape overall, anda proximal end portion of a webbing (not shown) formed in a longband-like shape is coupled and fixed to the take-up shaft 220. When thetake-up shaft 220 is rotated in one direction about its axial line(below, this direction will be called “the take-up direction”), thewebbing is taken up in layers on the outer peripheral portion of thetake-up shaft 220 from is proximal end side, and when the webbing ispulled out from its distal end side, the webbing is pulled out while thetake-up shaft 220 rotates in the other direction about its axial line inaccompaniment therewith (below, the rotational direction of the take-upshaft 220 when the webbing is pulled out will be called “the pulloutdirection”).

One end side of the take-up shaft 220 penetrates the leg plate 218 andprotrudes outward of the frame 212. An unillustrated lock mechanism isdisposed on the side of the leg plate 218. The lock mechanism isconfigured to include an acceleration sensor and is linked to a lockplate 222 that spans the distance between the leg plate 216 and the legplate 218 and to a torsion bar 224 that is disposed in the axial centerportion of the take-up shaft 220. When the vehicle suddenly deceleratesor the like, one end of the torsion bar 224 is restrained via the lockplate 222 by the actuation of the lock mechanism so that energyabsorption is performed and the rotation of the take-up shaft 220 in thepullout direction is deterred.

The other end side of the take-up shaft 220 penetrates the leg plate 216and protrudes slightly outward of the frame 212. A coupling screw 221formed in a hexagonal column shape is coaxially and integrally coupledto the other end side of the take-up shaft 220.

Further, a clutch case 201 serving as a case configuring a clutch 293pertaining to the second embodiment is disposed on the outer side of theleg plate 216. The clutch case 201 is formed in a substantiallyrectangular box-like shape by a metal material or the like (e.g., analuminum alloy, etc.) and opens toward the side opposite of the legplate 216. A cover clutch 290 comprising an iron plate or the like andserving as a case is disposed on the open side of the clutch case 201.

As shown in FIG. 13, two hook-and-lock pawls 200 that protrude in theplate thickness direction are disposed on the cover clutch 290. The twohook-and-lock pawls 200 are disposed at positions at a substantialdiagonal in mutually orthogonal end surfaces of the cover clutch 290 (inFIG. 13, the left side end surface and the lower side end surface), andsubstantially rectangular through holes 202 are formed in the centerportion of each of the hook-and-lock pawls 200. Further, groove-likeguide portions 204, together with which the hook-and-lock pawls 200 canfit, are formed in the side walls of the clutch case 201 at positionscorresponding to the two hook-and-lock pawls 200 of the cover clutch290, and engagement protrusions 206 serving as engagement portions aredisposed in the guide portions 204 at positions corresponding to thethrough holes 202 of the hook-and-lock pawls 200.

Thus, the cover clutch 290 is attached (provisionally fixed) to the openside of the clutch case 201 as a result of the hook-and-lock pawls 200being guided and positioned in the guide portions 204 of the clutch case201 and the engagement protrusions 206 being fitted together with andlocked in the through holes 202.

The clutch case 201 and the cover clutch 290 are integrally fixed to theleg plate 216 by screws 291.

As shown in FIG. 12, a circular through hole 294 is formed coaxiallywith the take-up shaft 220 in the center portion of the bottom wall ofthe clutch case 201, and the coupling screw 221 passes through thethrough hole 294. Further, the site in the vicinity of the through hole294 protrudes slightly in a circular fashion toward the side opposite ofthe leg plate 216, and a ring-like sliding surface 208 is formed.Moreover, a circular cylindrical bushing support portion 210 thatprotrudes toward the side opposite of the leg plate 216 is formed in thehole edge portion of the through hole 294. A bushing 212 (see FIG. 14and FIG. 15) formed in a ring-like shape by a resin material or the likeis supported on the bushing support portion 210.

A clutch gear portion 292 is disposed inside the clutch case 201. Theclutch gear portion 292 is disposed with a worm gear 234. The axis ofthe worm gear 234 is disposed in a state where it is perpendicular tothe take-up shaft 220, end portions of the worm gear 234 are supportedon the clutch case 201 via bushes 236 and 237, and one end side of theworm gear 234 is disposed protruding outward from the clutch case 201.Further, a steel ball 238 is housed in a bearing portion of the clutchcase 201 that supports the distal end portion of the worm gear 234, thesteel ball 238 contacts the distal end portion of the worm gear 234, andan adjust screw 240 is screwed into the bearing portion. The adjustscrew 240 pushes the steel ball 238 at its distal end portion to causethe steel ball 238 to be pressed against the distal end of the worm gear234. Thus, displacement in the axial direction of the worm gear 234 isregulated (thrust-adjusted). It will be noted that the steel ball 238may also be configured such that it is formed integrally on the distalend portion of the adjust screw 240 (such that the distal end portion ofthe adjust screw 240 is formed in a spherical shape). A clutch bodyportion 214 that configures the clutch 293 pertaining to the secondembodiment is disposed above the worm gear 234.

As shown in FIG. 14 and FIG. 15, the clutch body portion 214 is disposedwith a gear wheel 216 that configures a rotating body. The gear wheel216 is formed in a ring-like shape by a resin material or the like, isdisposed coaxially with the take-up shaft 220, and worm wheel teeth 218are formed on the outer peripheral portion of the gear wheel 216. Theworm wheel teeth 218 mesh with the above-mentioned worm gear 234.Further, plural (twelve in the second embodiment)circumferential-direction load receiving portions 220 are formed on theinner peripheral portion of the gear wheel 216 at predeterminedintervals along the radial direction of the gear wheel 216. Thecircumferential-direction load receiving portions 220 correspond tolater-described spring pawls 282 of a ring 276. Moreover, plural (six inthe second embodiment) baffle concave portions 222 are formed on the endsurface of one axial-line direction side (the side in the direction ofarrow A in FIG. 14 and FIG. 15) of the gear wheel 216 at constantintervals along the circumferential direction of the gear wheel 216. Thebaffle concave portions 222 correspond to later-described baffle pawls280 of the ring 276.

A rotor 224 that is formed in a discoid shape by a metal material or thelike (e.g., zinc aluminum alloy, etc.) and configures a rotating body isdisposed coaxially with the gear wheel 216 inside the gear wheel 216.The rotor 224 includes a bottomed circular cylindrical body portion 226and a flange portion 228 that protrudes in the radial direction at oneaxial-line direction side (the side in the direction of arrow B in FIG.14 and FIG. 15) of the body portion 226.

Plural outer teeth 230 are formed on the outer peripheral portion of thebody portion 226 at equidistant intervals along the circumferentialdirection of the body portion 226. Side walls of the outer teeth 230 onone side (the side in the direction of arrow C in FIG. 14 and FIG. 15)along the circumferential direction of the body portion 226 slant withrespect to the circumferential direction of the body portion 226, andside walls of the outer teeth 230 on the other side (the side in thedirection of arrow D in FIG. 14 and FIG. 15) along the circumferentialdirection of the body portion 226 are formed parallel along the radialdirection of the body portion 226 (in other words, the cross-sectionalshapes of the outer teeth 230 are trapezoidal). The outer teeth 230correspond to the later-described spring pawls 282 of the ring 276.

A substantially circular cylindrical housing portion 232 is formedcoaxially in the center portion of the bottom wall of the body portion226. A ring-like support shaft portion 233 protrudes coaxially on oneaxial-line direction side (the side in the direction of arrow A in FIG.14 and FIG. 15) of the housing portion 232. The support shaft portion233 is supported in a circular hole 235 formed in the cover clutch 290such that the support shaft portion 233 can freely rotate via alater-described rotation support portion 275 of a holder 270. Further,the previously mentioned bushing 212 is fitted, such that it can freelyrotate, in the other axial-line direction side (the side in thedirection of arrow B in FIG. 14 and FIG. 15), and the other axial-linedirection side of the housing portion 232 is supported, such that it canfreely rotate, on the clutch case 201 via the bushing 212. Thus, thebody portion 226 (the rotor 224) is configured to be rotatable about itsown axial line.

A ratchet 234 formed in a substantially ring-like shape by a steel plateor the like is housed inside the housing portion 232 of the body portion226. Outer teeth 236 that are ratchet teeth are formed on the outerperipheral portion of the ratchet 234. Further, a coupling hole 238 thathas a cross-sectionally hexagonal shape is formed in the axial centerportion of the ratchet 234, and the previously mentioned coupling screw221 is passed through the coupling hole 238 such that relative rotationis impossible. Thus, the take-up shaft 220 and the ratchet 234 areconfigured to rotate integrally via the coupling screw 221.

Further, a washer 209 formed in a ring shape by a resin material or thelike is integrally attached to the one axial-line direction side (theside in the direction of arrow A in FIG. 1 and FIG. 2) of the ratchet234. As shown in FIG. 16, a pair of pawl portions 208 and a pair ofcircular cylindrical baffle portions 210 are disposed on the ratchet 234side of the washer 209 (in FIG. 16, the far side in the directionperpendicular to the surface of the page). The pair of pawl portions 208hook and lock into a pair of hook-and-lock grooves 212 formed in thehole edge portion of the coupling hole 238 of the ratchet 234. Thus, thewasher 209 is attached to the ratchet 234 (movement of the washer 209along the axial line direction with respect to the ratchet 234 isregulated). Further, the baffle portions 210 fit into a pair of baffleconcave portions 214 formed in the end surface of the ratchet 234, andmovement of the washer 209 along the radial direction with respect tothe ratchet 234 is regulated (the washer 209 is positioned at apredetermined position of the ratchet 234).

A press fit portion 216 formed in a hexagonal cylinder shape is disposedin the center portion of the washer 209 opposite from the ratchet 234(in FIG. 16, the front side in the direction perpendicular to the page).Two crush rubs 218 that protrude inward in the radial direction aredisposed inside the cylinder of the press fit portion 216, and thecoupling screw 221 is press-fitted inside the cylinder of the press fitportion 216 in a state where it crushes these crush ribs 218. Thus,backlash of the ratchet 234 with respect to the coupling screw 221 isprevented, and the occurrence of striking sounds (backlash sounds)resulting from such backlash is prevented.

It will be noted that the end surface of the washer 209 opposite fromthe ratchet 234 (the side in the direction of arrow A in FIG. 14 andFIG. 15) slidably abuts against the ring-like bottom wall of the housingportion 232, and the end surface at the other axial-line direction side(the side in the direction of arrow B in FIG. 14 and FIG. 15) of theratchet 234 slidably abuts against the previously mentioned bushing 212.

As shown in FIG. 17, pair of guide holes 242 that are curved along thecircumferential direction of the body portion 226 is formed in thebottom wall of the body portion 226 of the rotor 224 at theradial-direction outer side of the housing portion 232. Sliders 244 thatare formed by a resin material or the like in substantially block-likeshapes and are curved along the circumferential direction of the bodyportion 226 are slidably attached to the guide holes 242. The pair ofsliders 244 is guided by the inner peripheral surface of the bodyportion 226 and by the outer peripheral surface of the housing portion232 and is configured to be relatively movable with respect to the bodyportion 226 (the rotor 224) within a predetermined range along the guideholes 242 (in FIG. 17, the illustration of later-described lock bars 254and torsion coil springs 264 is omitted).

Sliding pieces 246 protrude from one side (the side in the direction ofarrow A in FIG. 14 and FIG. 15) of the sliders 244 and, as shown in FIG.18, abut against the cover clutch 290. Further, retainers 248 aredisposed on the side of the sliders 244 opposite of the sliding pieces246. The retainers 248 are narrow metal pieces having elasticity and arebent in substantial “<” shapes. The retainers 248 are integrally coupledto the sliders 244 as a result of coupling portions 250 disposed inlongitudinal-direction center portions of the retainers 248 being fittedinto coupling holes 252 formed in the sliders 244, and are elasticallydeformed a predetermined amount as a result of bothlongitudinal-direction end portions of the retainers 248 being pushedagainst the previously mentioned sliding surface 208 of the clutch case201.

For this reason, the sliding pieces 246 of the sliders 244 are pushedagainst the cover clutch 290 by the elastic force of the retainers 248,and predetermined frictional force is imparted to the movement (relativemovement with respect to the rotor 224) of the sliders 244 along theguide holes 242. For this reason, when the rotor 224 rotates, thesliders 244 are retained in the case (the clutch case 201 and the coverclutch 290) temporarily by the frictional force acting on bothlongitudinal-direction end portions of the retainers 248 and the slidingpieces 246 and relatively move within a predetermined range along theguide holes 242 with respect to the rotor 224.

An escape prevention piece 247 is formed on one curve-direction endportion (the end portions at the side in the direction of arrow D inFIG. 14 and FIG. 15) of each of the sliders 244. Further, a pushretention piece 245 is formed on the other curve-direction end portion(the end portions at the side in the direction of arrow C in FIG. 14 andFIG. 15) of each of the sliders 244. The sliders 244 are retained on therotor 224 as a result of the escape prevention pieces 247 and the pushretention pieces 245 engaging with the hole edge portions of the guideholes 242 and the previously mentioned sliding pieces 246 engaging withthe housing portion 232 (the sliders 244 are prevented from escaping toone axial-line direction side of the rotor 224 (the side in thedirection of arrow B in FIG. 14 and FIG. 15) via the guide holes 242).

Further, the previously mentioned push retention pieces 245 correspondto a pair of lock bars 254. Each of the lock bars 254 is formed in asubstantial “<” shape by a steel plate or the like, is disposed on onecurve-direction end side of each of the sliders 244, and is disposedwith a ring-like bearing portion 256. The bearing portions 256 aresupported, such that they can freely rotate, by circular columnarsupport shafts 258 that protrude from the bottom wall of the bodyportion 226. A coupling piece 260 protrudes on the side (the side in thedirection of arrow C in FIG. 14 and FIG. 15) of each of the bearingportions 256 opposite from the sliders 244. The coupling pieces 260rotate about the support shafts 258 together with the bearing portions256, whereby the distal end portions of the coupling pieces 260penetrate hole portions 262 formed in the housing portion 232 of therotor 224 and mesh with the previously mentioned outer teeth 236 of theratchet 234. Further, the coupling pieces 260 are always biased in thedirection in which they mesh with the outer teeth 236 (the ratchet 234)by the biasing force of torsion coil springs 264. It will be noted thatthe torsion coil springs 264 are supported by circular columnar supportshafts 266 that protrude from the bottom wall of the body portion 226 ofthe rotor 224.

Release pieces 268 that correspond to the previously mentioned pushretention pieces 245 of the sliders 244 protrude from the sliders 244side (the side in the direction of arrow D in FIG. 14 and FIG. 15) ofthe bearing portions 256. The end portions of the release pieces 268facing the sliders 244 are formed as slanted surfaces that are slantedwith respect to the moving direction of the sliders 244 (the directionof arrow C and the direction of arrow D in FIG. 14 and FIG. 15).

Here, as shown in FIG. 19A and FIG. 19B, when the rotor 224 relativelymoves with respect to the sliders 244, the lock bars 254 move within apredetermined range toward and away from the sliders 244, and in a statewhere the lock bars 254 are close to the sliders 244 (the state shown inFIG. 19A), the release pieces 268 of the lock bars 254 enter the innersides (ratchet 234 sides) of the push retention pieces 245 of thesliders 244, whereby the release pieces 268 are retained in thedisengaged positions counter to the biasing force of the torsion coilsprings 264. In this state, the coupling pieces 260 of the lock bars 254move away from the ratchet 234.

On the other hand, in a state where the lock bars 254 have moved awayfrom the sliders 244 (the state shown in FIG. 19B), the release pieces268 of the lock bars 254 release the retention by the push retentionpieces 245 of the sliders 244. In this state, the coupling pieces 260 ofthe lock bars 254 are moved toward the ratchet 234 (engagementpositions) by the biasing force of the torsion coil springs 264, and thedistal end portions of the coupling pieces 260 mesh with the outer teeth236.

Further, here, as shown in FIG. 20, undercut portions that slant apredetermined angle (e.g., 10 degrees) with respect to the movingdirection of the sliders (the circumferential direction of the rotor224) are formed in the push retention pieces 245 of the sliders 244, andthe surfaces of the push retention pieces 245 facing the release pieces268 are formed as slanted surfaces 249 that slant with respect to themoving direction of the sliders 244. Further, undercut portions areformed in the release pieces 268 of the lock bars 254 in correspondenceto the previously mentioned undercut portions of the push retentionpieces 245, and the surfaces of the release pieces 245 facing the pushretention pieces 268 are formed as slanted surfaces 269 that slant withrespect to the moving direction of the sliders 244.

That is, the push retention pieces 245 and the release pieces 268 areconfigured to mesh and engage with each other a predetermined amount(predetermined dimension) d with respect to the radial direction of therotor 224. Additionally, when the lock bars 254 move away from thesliders 244, the slanted surfaces 249 of the push retention pieces 245cause the release pieces 268 to move the predetermined amount d towardthe ratchet 234, and the coupling pieces 260 are moved a predeterminedamount toward the side opposite of the ratchet 234 counter to thebiasing force of the torsion coil springs 264. Thus, predetermined dragarises in the separation movement of the lock bars 254 and the sliders.However, this drag is set to be sufficiently small in comparison to thefrictional force acting between both longitudinal-direction end portionsof the retainers 248 and the clutch case 201 and between the slidingpieces 246 of the sliders 244 and the cover clutch 290 by the elasticforce of the previously mentioned retainers 248.

It will be noted that, in the clutch body portion 214 pertaining to thesecond embodiment, the sliders 244 are ordinarily disposed close to thelock bars 254. Consequently, the lock bars 254 are ordinarily retainedin the disengaged positions (the state shown in FIG. 19A) as a result ofthe release pieces 268 being retained by the push retention pieces 245of the sliders 244.

A holder 270 formed in a ring-like shape by a resin material or the likeis disposed at the side (the side in the direction of arrow A in FIG. 5and FIG. 15) opposite from the rotor 224 via the lock bars 254. Theholder 270 is disposed with a ring-like body portion 272 and a pair ofretention pawls 274 disposed on the outer peripheral portion of the bodyportion 272. The body portion 272 regulates displacement of the lockbars 254 in the axial line direction with respect to the support shafts258 (the rotor 224), and the pair of retention pawls 274 regulatedisplacement of the torsion coil springs 264 in the axial line directionwith respect to the support shafts 266 (the rotor 224).

Further, the support shaft portion 233 of the rotor 224 penetrates acircular hole 273 formed in the center portion of the body portion 272.A rotation support portion 275 that protrudes slightly in a circularcylindrical shape toward the side opposite from the rotor 224 (towardthe cover clutch 290) is disposed on the hole edge portion of thecircular hole 273, and the support shaft portion 233 of the rotor 224 issupported, such that it can freely rotate, in the circular hole 235 ofthe cover clutch 290 via the rotation support portion 275.

A ring 276 comprising a metal material (e.g., SUS, etc.) havingelasticity is disposed at the radial-direction outer side of the holder270 and on one axial-line direction side (the side in the direction ofarrow A of FIG. 14 and FIG. 15) of the rotor 224. The ring 276 isdisposed with a cover portion 278 formed in a ring shape. Plural (six inthe second embodiment) baffle pawls 280 that protrude outward in theradial direction of the cover portion 278 are integrally formed on theouter peripheral portion of the cover portion 278. The baffle pawls 280fit together with the previously mentioned baffle concave portions 222of the gear wheel 216. Thus, the ring 276 is integrally coupled to thegear wheel 216 in the circumferential direction of the gear wheel 216.

Moreover, plural (twelve in the second embodiment) spring pawls 282 thatare formed in narrow plate shapes having elasticity (spring-ness) areintegrally formed on the outer peripheral portion of the cover portion278 at predetermined intervals along the circumferential direction ofthe cover portion 278. The proximal end portions of the spring pawls 282are integrally connected to the cover portion 278, thelongitudinal-direction intermediate portions of the spring pawls 282 arebent slightly toward the radial-direction inner side of the coverportion 278, and the distal end portions of the spring pawls 282 arebent toward the radial-direction outer side of the cover portion 278, sothat, overall, the spring pawls 282 curve along the circumferentialdirection of the cover portion 278.

As shown in FIG. 21A, the spring pawls 282 are disposed along thecircumferential direction of the rotor 224 and the gear wheel 216between the outer teeth 230 of the rotor 224 and the inner peripheralsurface of the gear wheel 216, and the inner side portions of the springpawls 282 are pushed against the outer teeth 230 of the rotor 224 by theelastic force of the spring pawls 282. Thus, the ring 276 is integrallyretained on the rotor 224.

Further, the outer side portions of the spring pawls 282 are engagedwith the inner peripheral surface of the gear wheel 216, and the gearwheel 216 is supported on the rotor 224 via the spring pawls 282. Inthis state, the movement of the gear wheel 216 in the axial linedirection is regulated by the baffle pawls 280 of the ring 276 and theflange portion 228 of the rotor 224. Moreover, in this state, thesliders 244, the lock bars 254, the torsion coil springs 264, and theholder 270 are prevented from coming off the rotor 224 by the coverportion 278 of the ring 276, and these configural members are retainedin predetermined installation positions.

Moreover, the distal end portions of the spring pawls 282 enter thevalley portions between the outer teeth 230 and abut against one sidewall of the outer teeth 230 (side walls at the sides formed parallelalong the radial direction of the body portion 226), and the proximalend portions of the spring pawls 282 abut against the previouslymentioned circumferential-direction load receiving portions 220 of thegear wheel 216. Thus, the gear wheel 216 and the rotor 224 areintegrally coupled together (their relative rotation is regulated) bythe spring pawls 282 with respect to their circumferential direction,and when the gear wheel 216 rotates, the gear wheel 216 and the rotor224 basically integrally rotate.

In this case, the rotational force of the gear wheel 216 in the take-updirection is transmitted to the proximal end portions of the springpawls 282 via the circumferential-direction load receiving portions 220and is transmitted to the outer teeth 230 of the rotor 224 from thedistal end portions of the spring pawls 282, such that the gear wheel216 receives along the circumferential direction the load acting thereonfrom the spring pawls 282 via the circumferential-direction loadreceiving portions 220 (the direction in which the gear wheel 216receives the load from the spring pawls 282 is set along the rotationaldirection thereof).

Moreover, in this case, as previously mentioned, because the springpawls 282 are metal pieces having elasticity, the coupling about theaxial line between the gear wheel 216 and the rotor 224 by the springpawls 282 is released as long as the rotational force arising due to therelative rotation of the gear wheel 216 with respect to the rotor 224 isof a size sufficient for causing the distal end portions of the springpawls 282 to escape from the valley portions between the outer teeth 230counter to the spring force (biasing force) of the spring pawls 282, andfor this reason, the transmission of the rotation of the gear wheel 216and the rotor 224 is cut off so that relative rotation between the gearwheel 216 and the rotor 224 becomes possible (see FIG. 21B).

Further, the rotational force of the gear wheel 216 in the pulloutdirection is transmitted to the baffle pawls 280 of the ring 276 via thebaffle concave portions 222 and is transmitted from the distal endportions of the spring pawls 282 of the ring 276 to the outer teeth 230of the rotor 224.

It will be noted that in the second embodiment, although the ring 276has a configuration disposed with twelve of the spring pawls 282, thenumber of the spring pawls 282 can be changed to six or eight, forexample, to adjust the load when the transmission of the rotation of thegear wheel 216 and the rotor 224 is cut off. However, in this case, thenumber of the circumferential-direction load receiving portions 220 andthe like must also be changed in correspondence to the number of thespring pawls 282.

Further, the load when the transmission of the rotation of the gearwheel 216 and the rotor 224 is cut off can also be changed by changingthe width dimension and the thickness dimension of the spring pawls 282or changing the depth dimension of the valley portions between the outerteeth 230 of the rotor 224.

A spacer 284 formed in a ring shape by a resin material or the like isdisposed on the side of the ring 276 opposite from the rotor 224 (theside in the direction of arrow A in FIG. 14 and FIG. 15). The spacer 284is sandwiched between the cover portion 278 of the ring 276 and thecover clutch 290. A pair each of coupling pieces 224 and 226 thatprotrude inward in the radial direction in correspondence to thepreviously mentioned pair of sliders 244 are disposed on the innerperipheral portion of the spacer 284. As shown in FIG. 22, the pair ofcoupling pieces 224 and the pair of coupling pieces 226 sandwich thesliding pieces 246 of the sliders 244 at both of their curve-directionsides. Thus, the pair of sliders 244 are coupled by the spacer 284, andthe pair of sliders 244 and the spacer 284 synchronously relatively move(relatively rotate) with respect to the rotor 224 and the lock bars 254.Moreover, in this case, frictional force acts on the spacer 284 by slidecontact (sliding) with the cover clutch 290.

It will be noted that in the second embodiment, although the pair ofsliders 244 and the spacer 284 are configured separately, the inventionis not limited to this and the pair of sliders 244 and the spacers 284may also be configured integrally.

The clutch 293 having the above-described configuration is configuredsuch that the gear wheel 216 of the clutch body portion 214 rotates whenthe worm gear 234 of the clutch gear portion 292 rotates, and the clutchbody portion 214 and the clutch gear portion 292 are integrallyassembled into a single case (the clutch case 201 and the cover clutch290), so that, overall, the clutch 293 is unitized.

As shown in FIG. 12, a spring complete 242 is disposed on the side ofthe cover clutch 290. The spring complete 242 houses a spiral spring(not shown) inside. The end portion of the spiral spring at the outerside in the spiral direction is latched to the case body, and the endportion of the spiral spring at the inner side in the spiral directionis latched to the distal end of the coupling screw 221 penetrating theclutch body portion 214, and the spiral spring biases the take-up shaft220 in the take-up direction.

Further, a motor 244 and a motor gear portion 246 are disposed below thetake-up shaft 220 between the leg plate 216 and the leg plate 218.

As shown in FIG. 23, the motor 244 and the motor gear portion 246 aredisposed with a housing 248. The motor 244 is attached to one side ofthe housing 248 by screws, and the motor gear portion 246 is disposed onthe other side of the housing 248. The motor 244 is fixed to the oneside of the housing 248 in a state where the distal end side (the outputside) of a rotating shaft 250 faces the housing 248, and the distal end(the output side) of the rotating shaft 250 protrudes toward the otherside of the housing 248 (the side of the motor gear portion 246).

A pinion 272 having spur teeth on its outer periphery is attached to thedistal end of the rotating shaft of the motor 244 protruding toward theother side of the housing 248 (the side of the motor gear portion 246).Further, a gear 274 and a gear 276, each of which is formed asouter-toothed spur gears, are housed in the motor gear portion 246 in astate where they are meshed with each other. The gear 274 and the gear276 are disposed in a state where their axes are parallel to therotating shaft of the motor 244. The gear 274 meshes with the pinion272, and the gear 276, which serves as a final spur gear, is detachablycoupled to the previously mentioned one end portion of the worm gear 234protruding outward from the clutch case 201. For this reason, when themotor 244 is driven, drive force is transmitted via the pinion 272, thegear 274, and the gear 276, and the worm gear 234 is rotated.

Further, the pinion 272, the gear 274, and the gear 276 are covered by acover gear 278 attached to the housing 248. Pawl portions 280 aredisposed on the cover gear 278, and the pawl portions 280 fit togetherand hook-and-lock with pawl receiving portions 282 disposed on thehousing 248, whereby the cover gear 278 is fixed to the housing 248.

In this manner, the motor 244 and the motor gear portion 246 are bothintegrally assembled to the single housing 248, so that, overall, theyare unitized.

As for the motor 244 and the motor gear portion 246 having the aboveconfiguration, as shown in FIG. 24, an attachment stay 284 integrallydisposed on the housing 248 is detachably attached by screws to theclutch case 201 (i.e., the frame 212) housing the clutch body portion214 and the clutch gear portion 292. In a state where the housing 248 isattached to the clutch case 201 (the frame 212), the rotating shaft 250of the motor 244 is orthogonal to the take-up shaft 220 and the outputside of the motor 244 faces the side of the frame 212 opposite from theback plate 214, and the motor 244 is positioned between the pair of theleg plate 216 and the leg plate 218 and directly below the take-up shaft220.

Moreover, the previously mentioned motor 244 is configured to beactuated on the basis of a detection signal of a forward monitoringdevice or the like, for example.

Next, the action of the second embodiment will be described.

In the webbing take-up device 210 having the above-describedconfiguration, the sliders 244 of the clutch body portion 214 areordinarily disposed close to the lock bars 254, as shown in FIG. 19A.Consequently, the release pieces 268 of the lock bars 254 are ordinarilyretained by the push retention pieces 245 of the sliders 244, and thecoupling pieces 260 of the lock bars 254 are separated from the outerteeth 236 of the ratchet 234. For this reason, the ratchet 234 (thetake-up shaft 220) is free to relatively rotate with respect to therotor 224.

Consequently, when a passenger is seated in the seat of the vehicle andpulls out the webbing stored in the webbing take-up device 210, thewebbing is pulled out while the take-up shaft 220 rotates in the pulloutdirection. Thus, the passenger places the webbing around his/her bodyand causes a tongue plate disposed on the webbing, for example, toengage with a buckle device, whereby the passenger can wear the webbingaround his/her body.

When an obstacle is present in front of the vehicle while the vehicle istraveling and the distance between the vehicle and the obstacle (thedistance from the vehicle to the obstacle) comes within a predeterminedrange, the driving of the motor 244 is started and the rotating shaft250 is suddenly rotated.

When the rotating shaft 250 of the motor 244 is rotated, the rotationalforce is transmitted to the gear wheel 216 of the clutch body portion214 via the pinion 272, the gear 274, and the gear 276 of the motor gearportion 246 and the worm gear 234 of the clutch gear portion 292, andthe gear wheel 216 is suddenly rotated in the take-up direction. Therotation of the gear wheel 216 in the take-up direction is transmittedto the proximal end portions of the spring pawls 282 of the ring 276 viathe circumferential-direction load receiving portions 220 and istransmitted to the outer teeth 230 of the rotor 224 from the distal endportions of the spring pawls 282, and the rotor 224 is suddenly rotatedin the take-up direction.

At this time, because the sliders 244 are retained in the case (theclutch case 201 and the cover clutch 290) by frictional force acting onthe sliding pieces 246 and the retainers 248, the rotor 224 relativelymoves within a predetermined range with respect to the sliders 244, andthe lock bars 254 supported on the rotor 224 move away from the sliders244.

For this reason, the retention of the release pieces 268 by the pushretention pieces 245 is released, the coupling pieces 260 of the lockbars 254 are moved toward the ratchet 234 by the biasing force of thetorsion coil springs 264, and the distal end portions of the couplingpieces 260 mesh with the outer teeth 236 of the ratchet 234 (see arrow Ein FIG. 19B). Thus, the rotation of the rotor 224 in the take-updirection is transmitted to the ratchet 234 via the lock bars 254, andthe ratchet 234 is suddenly rotated in the take-up direction. Becausethe ratchet 234 is integrally coupled to the take-up shaft 220, thetake-up shaft 220 is suddenly rotated in the take-up direction togetherwith the ratchet 234.

Thus, the webbing is taken up on the take-up shaft 220, slight loosenessof the webbing known as “slack” is eliminated and the restraining forceof the webbing with respect to the body of the passenger is improved, sothat even if the passenger thereafter performs the operation of suddenvehicular braking (sudden braking) and the vehicle suddenly decelerates,the webbing reliably holds the body of the passenger.

Moreover, in a state where the “slack” has been eliminated as describedabove, the body of the passenger becomes an obstacle, so that basicallyno more of the webbing becomes able to be taken up on the take-up shaft220. For this reason, a load equal to or greater than a predeterminedvalue acts on the take-up shaft 220 from the webbing, and as a result, aload (overload) equal to or greater than a predetermined value acts onthe rotor 224 via the ratchet 234 and the lock bars 254. When a loadequal to or greater than a predetermined value acts on the rotor 224, asshown in FIG. 21A and FIG. 21B, the spring pawls 282 become elasticallydeformed, the distal end portions of the spring pawls 282 escape fromthe valley portions between the outer teeth 230 of the rotor 224, andrelative idling between the gear wheel 216 and the rotor 224 becomespossible (a “load limiter mechanism”; see arrow F in FIG. 21B).

Thus, the take-up shaft 220 coupled to the rotor 224 via the ratchet 234and the lock bars 254 can be prevented from being rotated in the take-updirection with a force more than necessary by the driving force of themotor 244, and the webbing can be prevented from tightening around thebody of the passenger with a force more than necessary.

Moreover, in this state, because the outer teeth 236 of the ratchet 234are formed as ratchet teeth, as shown in FIGS. 25A and 25B, when theratchet 234 (the take-up shaft 220) tries to relatively rotate in thetake-up direction with respect to the rotor 224 (see arrow H in FIG.25B), the lock bars 254 jump over the outer teeth 236 of the ratchet 234(see arrow G in FIG. 25B) and allow the relative rotation of the ratchet234 (the take-up shaft 220) in the take-up direction with respect to therotor 224.

Thus, as described above, when, for example, a collision of the vehiclecannot be avoided in a state where the “slack” has been eliminated, itis also possible to cause the take-up shaft 220 to be forcibly rotatedin the take-up direction by a separate pretensioner mechanism or thelike. In this case, the restraining force of the webbing on the body ofthe passenger can be further raised, and injury to the passenger in theevent of a vehicle collision can be kept to a minimum.

When the danger of such a vehicle collision has been avoided, therotating shaft 250 of the motor 244 is reversely rotated. The rotationalforce of the rotating shaft 250 is transmitted to the gear wheel 216 ofthe clutch body portion 214 via the pinion 272, the gear 274, and thegear 276 of the motor gear portion 246 and the worm gear 234 of theclutch gear portion 292, and the gear wheel 216 is suddenly rotated inthe pullout direction (see arrow D in FIG. 26A).

The rotation of the gear wheel 216 in the pullout direction istransmitted to the baffle pawls 280 of the ring 276 via the baffleconcave portions 222 of the gear wheel 216 and is transmitted to theouter teeth 230 of the rotor 224 from the distal end portions of thespring pawls 282 of the ring 276, and the rotor 224 is suddenly rotatedin the pullout direction.

At this time, because the sliders 244 are retained in the case (theclutch case 201 and the cover clutch 290) by frictional force acting onthe sliding pieces 246 and the retainers 248, the rotor 224 relativelymoves within a predetermined range with respect to the sliders 244, andthe lock bars 254 supported on the rotor 224 move toward the sliders244.

For this reason, the push retention pieces 245 of the sliders 244 pushthe slanted end surfaces of the release pieces 268 of the lock bars 254,whereby the release pieces 268 are moved toward the ratchet 234 counterto the biasing force of the torsion coil springs 264 (see arrow J inFIG. 26B), and the coupling pieces 260 of the lock bars 254 move awayfrom the outer teeth 236 of the ratchet 234. Moreover, when the lockbars 254 move toward the sliders 244, the release pieces 268 of the lockbars 254 enter the inner sides (toward the ratchet 234) of the pushretention pieces 245 of the sliders 244 so that the lock bars 254 areretained in the disengaged positions (the state shown in FIG. 26B).Thus, the rotor 224 and the ratchet 234 again become relativelyrotatable so that free rotation of the take-up shaft 220 becomespossible.

Here, in the clutch body portion 214 of the webbing take-up device 210,the push retention pieces 245 of the sliders 244 and the release pieces268 of the lock bars 254 are configured to mesh and engage with eachother via the slanted surfaces 249 and the slanted surfaces 269, andpredetermined drag arises when the sliders 244 try to move away from thelock bars 254. Consequently, for example, even when the sliders 214 tryto move away from the lock bars 254 due to intense vibration or the likeof the vehicle during traveling, the separation movement is deterred bythe predetermined drag resulting form the meshing and engagement betweenthe push retention pieces 245 and the release pieces 268, and theengaged state between the push retention pieces 245 of the sliders 244and the release pieces 268 of the lock bars 254 is maintained. Thus, theretention of the lock bars 254 by the sliders 244 is prevented frombeing inadvertently released, and erroneous linkage of the clutch bodyportion 214 is prevented.

Moreover, in the clutch body portion 214 of the webbing take-up device210, the pair of sliders 244 that retain the pair of lock bars 254 inthe positions where the lock bars 254 are disengaged from the ratchet234 are coupled by the spacer 284 and are synchronous. Consequently, forexample, even when one of the sliders 244 tries to relatively move withrespect to the rotor 224 (one of the lock bars 254) due to intensevibration or the like of the vehicle, the retention of the one lock bar254 by the one slider 244 is not released as long as the other slider244 and the spacer 284 do not relatively move with respect to the rotor224.

That is, in the clutch body portion 214, the retention of the lock bars254 by the sliders 144 is not released as long as the sliders 244 andthe spacer 284 do not relatively move at the same time with respect tothe lock bars 254.

Moreover, in this case, the spacer 284 that couples and synchronizes thepair of sliders 244 is configured to slide against the cover clutch 290.For this reason, because frictional force acts on the spacer 284, thepair of sliders 244 and the spacer 284 can be more reliably preventedfrom inadvertently relatively moving with respect to the rotor 224, thatis, the pair of lock bars 254, and erroneous linkage of the clutch bodyportion 214 can be more reliably prevented.

Further, in the clutch body portion 214 of the webbing take-up device210, the load (overload) at the time of rotation transmission cutoff ofthe gear wheel 216 and the rotor 224 can be adjusted by changing thenumber of the twelve spring pawls 282 disposed on the ring 276 to six oreight, for example. Consequently, the setting of the load is easy.

Further, in the clutch body portion 214 of the webbing take-up device210, the coupling screw 221 coaxially and integrally coupled to thetake-up shaft 220 penetrates the coupling hole 238 of the ratchet 234such that relative rotation is impossible and is press-fitted into thepress fit portion 216 of the washer 209 integrally attached to theratchet 234. Consequently, backlash of the ratchet 234 with respect tothe coupling screw 221 is prevented, and the occurrence of strikingsounds (backlash sounds) resulting from such backlash is prevented.

Moreover, the press fit portion 216 of the washer 209 includes the crushribs 218 that are crushed by the press-fitting of the coupling screw221. Consequently, the load when the coupling screw 221 is press-fittedinto the press fit portion 216 can be easily adjusted by changing thesize and the shape of the crush ribs 218.

Further, in the clutch 293 of the webbing take-up device 210, withrespect to the clutch case 201 and the cover clutch 290 that house theclutch body portion 214 and the clutch gear portion 292, the coverclutch 290 is attached to the open side of the clutch case 201 as aresult of the through holes 202 of the two hook-and-lock pawls 200 thatprotrude in the plate thickness direction fitting andhooking-and-locking together with the two engagement protrusions 206disposed on the side wall of the clutch case 201. Consequently, when thecover clutch 290 is to be attached to the clutch case 201, it is notnecessary to use tools, and the cover clutch 290 can be easily andquickly attached by manual work.

Moreover, in this case, the guide portions 204 that guide and positionthe hook-and-lock pawls 200 of the cover clutch 290 are disposed in theclutch case 201. Thus, the work of attaching the cover clutch 290 to theclutch case 201 becomes even easier.

Further, in this case, because the guide portions 204 have groove shapesand the hook-and-lock pawls 200 fit together with the guide portions204, the hook-and-lock pawls 200 can be prevented from becomingdisplaced (escaping) along the side wall of the clutch case 201 when thecover clutch 290 is to be attached to the clutch case 201. Consequently,it is not necessary to set the two hook-and-lock pawls 200 to positionswhere the clutch case 201 is sandwiched by the hook-and-lock pawls 200(e.g., in FIG. 13, the right side end surface and the left side endsurface of the cover clutch 290), and it becomes possible to dispose thehook-and-lock pawls 200 on mutually orthogonal end surfaces of the coverclutch 290 (in FIG. 13, the left side end surface and the lower side endsurface) as in the second embodiment. Thus, the degree of freedom withwhich the positions of the hook-and-lock pawls 200 can be set isimproved.

As described above, in the webbing take-up device 210 pertaining to thesecond embodiment, erroneous linkage of the clutch body portion 214 canbe prevented. Further, the load (overload) at the time of rotationtransmission cutoff between the gear wheel 216 and the rotor 224 can beeasily set. Moreover, the attachment of the cover clutch 290 to theclutch case 201 becomes easy. Further still, backlash between theratchet 234 and the coupling screw 221 is prevented, and the occurrenceof backlash sounds is prevented. Further, the load when the couplingscrew 221 is press-fitted into the washer 234 can be easily adjusted.

The clutch body portion 214 pertaining to the second embodiment has aconfiguration where the slanted surfaces 249 are disposed on the pushretention pieces 245 of the sliders 244, the slanted surfaces 269corresponding to the slanted surfaces 249 are disposed on the releasepieces 268 of the lock bars 254, and predetermined drag is caused toarise in the separation movement of the lock bars 254 and the sliders asa result of the push retention pieces 245 and the release pieces 268being caused to mesh and engage with each other. However, the inventionis not limited to this. Protrusions may be disposed on the pushretention pieces 245 of the sliders 244 and on the release pieces 268 ofthe lock bars 254, so that predetermined drag is caused to arise in theseparation movement of the lock bars 254 and the sliders as a result ofcausing these protrusions to mesh and engage with each other. Further, atreatment to raise frictional force may be administered to the contactportions of the push retention pieces 245 and the release pieces 268 tocause predetermined drag to arise in the separation movement of the lockbars 254 and the sliders.

Further, although the webbing take-up device 210 pertaining to thesecond embodiment was configured such that the rotation of the rotatingshaft 250 of the motor 244 was transmitted to the take-up shaft 220 bythe clutch 293 to cause the take-up shaft 220 to rotate in the webbingtake-up direction, the webbing take-up device is not limited to this andmay also be configured such that the rotation of the rotating shaft 250of the motor 244 is transmitted to the take-up shaft 220 by the clutchto cause the take-up shaft 220 to rotate in the webbing pulloutdirection. This point is the same with respect also the third embodimentbelow.

Third Embodiment

Next, a third embodiment of the present invention will be described. Itwill be noted that, in regard to configurations/actions that arebasically the same as those of the second embodiment, the same referencenumerals as those in the second embodiment will be used and descriptionthereof will be omitted.

In FIG. 27A and FIG. 27B, the partial configuration of a clutch bodyportion 390 that is a configural member of a webbing take-up devicepertaining to the third embodiment of the invention is shown in sideview.

The clutch body portion 390 basically has the same configuration as thatof the clutch body portion 114 pertaining to the previously mentionedsecond embodiment, but is different in the following respect.

The clutch body portion 390 is disposed with sliders 391. The sliders391 basically have the same configuration as that of the sliders 244pertaining to the second embodiment, but include push portions 392instead of the previously mentioned push retention pieces 245. Slantedsurfaces 393 that are slanted with respect to the moving direction ofthe sliders 391 (the circumferential direction of a rotor 324) areformed on the push portions 392.

Further, lock bars 394 are disposed on the push portion 392 (the slantedsurface 393) side of the sliders 391. The lock bars 394 basically havethe same configuration as that of the lock bars 254 pertaining to thesecond embodiment, but release edges 395 that protrude toward the sideof bearing portions 356 opposite from the sliders 391 are always biasedtoward a ratchet 334 by torsion coil springs 364. For this reason,coupling pieces 396 that are disposed on the bearing portions 356 suchthat they protrude toward the sliders 391 are always biased toward theopposite side of the ratchet 334 (in the disengagement direction) andare always separated from the ratchet 334 (the state shown in FIG. 27A).

In the clutch body portion 390, when the rotor 324 rotates in thetake-up direction (in the direction of arrow C in FIG. 27B), the rotor324 relatively moves within a predetermined range with respect to thesliders 391 and the lock bars 394 supported on the rotor 324 move towardthe sliders 391 because the sliders 391 are retained on the clutch case201 and the cover clutch 290 (both not shown) by frictional force actingon sliding pieces 346 and retainers 348 (not shown). When the lock bars394 move toward the sliders 391, the coupling pieces 396 of the lockbars 394 are pushed toward the ratchet 134 by the slanted surfaces 393of the push portions 392, and the distal end portions of the couplingpieces 396 mesh with outer teeth 336 of the ratchet 334 (see arrow K inFIG. 27B).

On the other hand, when the rotor 324 rotates in the pullout direction(the direction of arrow D in FIG. 27A), the rotor 324 relatively moveswithin a predetermined range with respect to the sliders 391 and thelock bars 394 supported on the rotor 324 move away from the sliders 391because the sliders 391 are retained on the clutch case 101 and thecover clutch 290 (both not shown) by frictional force acting on thesliding pieces 346 and the retainers 348 (not shown). When the lock bars394 move away from the sliders 391, the pushing on the coupling pieces396 of the lock bars 394 by the slanted surfaces 393 of the pushportions 392 is released and the coupling pieces 396 are again moved toand retained in the positions where they are disengaged from the ratchet334 (see arrow L in FIG. 27A).

Even in the clutch body portion 390 having this configuration, actionand effects that are basically the same as those of the clutch bodyportion 114 pertaining to the second embodiment are provided.

In particular, in the clutch body portion 390, the coupling pieces 396of the lock bars 394 are always biased by the torsion coil springs 364in the direction in which the coupling pieces 396 are disengaged fromthe ratchet 334. Consequently, even when intense vibration arises in thevehicle during travel, the coupling pieces 396 of the lock bars 394 areretained by the biasing force of the torsion coil springs 364 in thepositions where the coupling pieces 396 are disengaged from the ratchet334. Thus, the coupling pieces 396 of the lock bars 394 are preventedfrom inadvertently engaging with the ratchet 334, and erroneous linkageof the clutch body portion 390 is prevented.

INDUSTRIAL APPLICABILITY

The present invention is as described above, and the webbing take-updevice pertaining to the present invention can not only transmit to thetake-up shaft just the rotation from the motor by the clutch, but canalso be configured simply and compactly. Further, the webbing take-updevice of the present invention can prevent erroneous linkage of theclutch. Consequently, its range of utilization is extremely wide.

DESCRIPTION OF THE REFERENCE NUMERALS

-   10, 210 Webbing take-up devices-   20, 220 Take-Up Shafts-   44, 244 Motors-   100, 293 Clutches-   101, 201 Clutch Cases (Cases)-   102, 290 Cover Clutches (Cases)-   116, 216 Gear Wheels-   124, 224, 324 Rotors-   134, 234, 334 Ratchets-   144, 244, 391 Sliders-   154, 254, 394 Lock Bars-   182, 282 Spring Pawls

1. A webbing take-up device comprising: a take-up shaft around which awebbing for restraining a passenger is wound such that the webbing canbe taken up and pulled out; a motor; and a clutch that is mechanicallyintervened between the motor and the take-up shaft, transmits therotation of the motor to the take-up shaft to cause the take-up shaft torotate, and cuts off the transmission of rotation arising at the take-upshaft side to prevent that rotation from being transmitted to the motor,wherein the clutch includes a rotating body that is disposed coaxiallywith respect to the take-up shaft and rotates as a result of therotation of the motor being transmitted to the rotating body, slidersthat are configured to be relatively movable within a predeterminedrange with respect to the rotating body and include push retentionpieces that protrude toward one side in the moving direction, and lockbars that are disposed on the rotating body, are always biased in adirection in which they engage with the take-up shaft, include releasepieces that protrude toward the push retention pieces of the sliders,and are ordinarily retained in positions where the lock bars aredisengaged from the take-up shaft as a result of the release piecesengaging with the push retention pieces, and when the rotating bodyrotates in one direction about an axial line of the rotating body, thelock bars move away from the sliders such that the retention isreleased, engage with the take-up shaft by a biasing force, and transmitto the take-up shaft the rotation of the rotating body in the onedirection about the axial line of the rotating body, and when therotating body rotates in the other direction about its axial line, thelock bars move toward the sliders and are moved to and retained in thedisengaged positions as a result of the release pieces engaging with thepush retention pieces, and at least one of the push retention pieces ofthe sliders and the release pieces of the lock bars include retentionportions that cause predetermined drag to arise with respect to themovement of the sliders away from the lock bars when the rotating bodyis stopped.
 2. The webbing take-up device of claim 1, wherein theretention portions are configured as slanted surfaces that cause thelock bars to move a predetermined amount in the direction in which thelock bars disengage from the take-up shaft counter to the biasing forcewhen the sliders move away from the lock bars.
 3. A webbing take-updevice comprising: a take-up shaft around which a webbing forrestraining a passenger is wound such that the webbing can be taken upand pulled out; a motor; and a clutch that is mechanically intervenedbetween the motor and the take-up shaft, transmits the rotation of themotor to the take-up shaft to cause the take-up shaft to rotate, andcuts off the transmission of rotation arising at the take-up shaft sideto prevent that rotation from being transmitted to the motor, whereinthe clutch includes a rotating body that is disposed coaxially withrespect to the take-up shaft and rotates as a result of the rotation ofthe motor being transmitted to the rotating body, sliders that areconfigured to be relatively movable within a predetermined range withrespect to the rotating body, and lock bars that are disposed on therotating body and are always biased in a direction in which the lockbars disengage from the take-up shaft, and when the rotating bodyrotates in one direction about an axial line of the rotating body, thelock bars engage with the take-up shaft as a result of being pushedtoward the take-up shaft by the sliders and transmit to the take-upshaft the rotation of the rotating body in the one direction about theaxial line of the rotating body, and when the rotating body rotates inthe other direction about its axial line, the lock bars are moved to andretained in the disengaged positions by the biasing force as a result ofthe pushing by the sliders being released.
 4. A webbing take-up devicecomprising: a take-up shaft around which a webbing for restraining apassenger is wound such that the webbing can be taken up and pulled out;a motor; and a clutch that is mechanically intervened between the motorand the take-up shaft, transmits the rotation of the motor to thetake-up shaft to cause the take-up shaft to rotate, and cuts off thetransmission of rotation arising at the take-up shaft side to preventthat rotation from being transmitted to the motor, wherein the clutchincludes a rotating body that is disposed coaxially with respect to thetake-up shaft and rotates as a result of the rotation of the motor beingtransmitted to the rotating body, a pair of sliders that are configuredto be relatively movable within a predetermined range with respect tothe rotating body, a spacer that couples together and synchronizes thepair of sliders, and a pair of lock bars that are disposed on therotating body and are ordinarily retained by the sliders in positionswhere the lock bars are disengaged from the take-up shaft, and when therotating body rotates in one direction about an axial line of therotating body, the retention is released such that lock bars engage withthe take-up shaft and transmit to the take-up shaft the rotation of therotating body in the one direction about the axial line of the rotatingbody, and when the rotating body rotates in the other direction aboutits axial line, the lock bars are moved to and retained in thedisengaged positions by the sliders, and the clutch includes a case andthe spacer slidingly contacts the case.